This is a difficult equation to solve. You are trying to boost the effectiveness of an absorbent product for extended wear (and presumably heavy use) while in a seated position. Arguably, the seated position is the most difficult situation absorbent products contend with (that or side sleeping). Usually adding "boosters" can actually cause leaks as they fill the space where the leak guards are and begin to force fluids right out the sides. And in this position I would recommend not using a booster anywhere but upfront. I've found there is no need, and could be detrimental, if the boost has any bias to the rear.
You are going to need to experiment with whatever system you choose to use. However, I can lend some insights I've discovered when I know I'm going to be seated for a long time:
1) You will need a LOT of room up front. You are asking your product to work almost entirely from the front and, in general, that is where the least amount of padding is. If your product is tight up front, you will leak. If your product swells a lot, it can make things tight as the room is taken up, and you will leak. You will need to make a lot of room up front while still maintaining a secure and viable leg seal. This means you need to experiment with putting your products on in different fashions. Try taping your product on with a bias towards the front, try taking that to an extreme. Test it out.
2) You should use a product that promotes wicking. For the most part, if a product wicks well it doesn't absorb much. This is due to the different composition of materials. For a product to wick it relies on pulp and other fillers, but they don't absorb much. For a product to absorb a great deal, a great deal of SAP is used. Awesome material that's great at locking in great amounts of moisture, but doesn't wick well. There are some great products out there that combine the best of these features and by far the best I've ever found is NorthShore Supremes. These have great absorbency and wick far better than any product I've ever tried. In a seated position, you can expect to use almost ALL of the available padding front and rear prior to leaking.
3) If using a High SAP product, try augmenting it's wicking abilities. Almost like a "booster" you can help a high absorbency product wick better by placing a different medium inside the product. You could use a washcloth the crotch leading to the back. This could help promote the spread of liquids to the rear of the product. This also feels wet. You may need to use more powder than normal or a barrier cream as this wet cloth will be next to your skin.
4) "Cool people wear their hats backward". This method can also work well with high absorbency products. Most of them tend to have a LOT of padding in the rear, and much more than what is offered in the front of the product. However some of them don't have as much SAP in the back as they do in the front (ABDL's love the way something swells). But products tend to naturally have much more room in the seat for expansion purposes (usually intended for the introduction of solids). All of these features combined can mean excellent absorbency in the seated position. You will naturally have MUCH more padding available, it will wick much better and all over the front, it will tend to wick much better towards the "back" where there is much more SAP, and you've reduced the amount of padding that you're actually sitting on which in turn reduces the chances of press-out leaking. In this scenario (if you still have very good leg seals, and I've found most of the time they're even better) you should have MORE than enough room up front for expansion. This also means that you have enough room for an actual booster. Seriously, this expedient method has worked wonders for me with high capacity products in seated positions.
5) "Diaper Sandwich" (dude bits only). This method works great on a number of levels, but it does require at least one cloth backed product. This works best if you have a good cloth backed diaper, and a high absorbency plastic backed diaper. Put the cloth backed product on as you normally would and locate your gentleman's sausage. Mark it's location and remove the product. Use a very sharp object to cut a horizontal slit that will provide a very snug fit when not excited. Flip the diaper over and put it on backwards. You can still tape as normal by twisting the tapes so they are the right way, that way they aren't against your skin. This is where the turtle can come out of its shell. Ensure that your goods are pulled all the way through and the diaper is sitting snuggly against your skin (this actually feels amazing, it's the closest fit you'll ever have and yet nothing is being squished). Now apply another (high capacity) diaper as normal. You've effectively swathed your man pipe in a cocoon of diaper goodness. You've effectively doubled the amount of absorbency you have up front with the added benefit of staying drier than you ever have before (nothing in contact with the actual diaper other than the dipstick). The downside is that you will have some SAP that comes out (change in the bathroom) and if you ever have need for protection from the other end...it's not pleasant.
6) "Go big or go home". This method works if, and ONLY if, you can still achieve great leg seals. You can simply go a size up in your protection. Stepping from a medium to a large will usually net some more absorbency, but more importantly MUCH more room for expansion. If you can still achieve great leg seals, try going up a size. You might find you have more than enough room for fitting a booster in without going through the hassle of these other methods.
7) WARNING: This method can NOT be recommended if you don't understand your body very well!
Much like those that have to deal with brown accidents can avert them or hold them off with the use of preventative enemas, those that deal with frontal leakage (like myself) can prevent or reduce the severity of accidents my reducing output. To reduce output you have to reduce your intake. Try cutting fluid intake up to a day ahead of time (do NOT dehydrate yourself!). If you can reduce fluid intake sufficiently (without endangering yourself) you can significantly reduce your fluid output. However, this can absolutely have an impact on your health if take to an extreme. Also, you are in danger of over indulging in fluids when you start drinking again, which completely negates why you did this in the first place.
8) Stretch before a marathon. Just like any arduous physical endeavor it behooves you to stretch out first. You should practice holding as much as you can for as long as you can. BUT DON'T TAKE IT TOO FAR! If it hurts, seriously hurts, STOP and just let it go. Stretching can help you hold a greater volume for a longer period of time, but you have to be very careful about controlling your release (if you still have the luxury of controlling it, some of us don't anymore, or at most don't have much). This leads me to number 9.
9) Metered output. If you can control it, you should really strive for very small and very slow releases. This ensures ample time for absorption and wicking. While seated is NOT the time for flooding. Back when I wore for fun and still had great control I found that you could combine stretching with controlled release to greatly extend the life of a product. Hold as much as you can until it truly become uncomfortable, then release a bit slowly to ease the discomfort, but do not drain completely! This method requires a great deal of control (and I only had this kind of control briefly in my late teens and very early twenties) but it works very well. The unfortunate side effect is that you will be on the edge of discomfort for an extended period of time. The method works, but it may not feel very good and does require great concentration.
10) Wear plastic pants! They can help contain leaks, but you will need to also have something a bit absorbent between your diaper and plastic pants for them to work really well. This can be as simple as a pair of regular underwear. They don't add a lot of bulk, but can help soak up any leaks without creating a puddle in the plastic pants. Also if you decide to change out of your diaper, and haven't leaked, you will have something to wear. This can also come in handy so that when you change and empty, you can continue to hold as much as you can. If you dribble or leak a bit you won't actually wet your pants.
If you've made it this far...I'm sorry. This is a problem that I've struggled to solve for a long time. As my control has diminished (nighttime issues became daytime problems), and I've found myself in this situation more and more, I've continued to try and solve it. It's something that I've considered and experimented with quite a bit. I honestly feel that the seated position, extended wear, and high fluid intake situation is the hardest for any product to cope with. There are a fair few professional drivers on here that could also lend you some great insights and I look forward to seeing them! I highly suggest you experiment with several of these individually and in combination prior to your deadline. You will need to know for sure if your method will work!
And they found diapers but they didn't know what they were at first so they asked to have me put out the contents and I was like, it would have to be done in private. So they took me to a room and I pulled out my diaper stuff and they were like oh I'm so sorry.
As she checked my back. She just asked if there was anything wrong. I was like nope just like wearing them 