Don't get me wrong the belt style products are still great in the right scenario, being able to undo the front and use a toilet is really handy, and the fact they are a little slimmer both in thickness and width/pad size makes them quite discreet and they are really easy to change from many positions and in cramped spaces.
But they are designed for light IC, either a few dribbles here and there or a regular small and slow stream, they can hold quite a lot of small dribbles but are not as good at taking a full or even half bladder load in a short time. Even though capacity wise they can handle that much, the slimness, shorter guards and general shaping/profile means when releasing larger amounts at once it doesn't get absorbed fast enough and has nowhere else to go but out of the legs.
They are also better suited to people who are very active and need the freedom to move around without any bulk getting in the way.
Going with tape on style, with most brands now you can still undo the tapes to take it off and use a toilet and then reattach them, especially so with the cloth backed, but if you do that too many times they do begin lose grip. This does however mean properly taking it off and putting it back on again which can be a pain if you are less mobile.
Of course you also have the option if just needing a wee in the toilet, of simply pulling aside the crotch section and pulling your manhood out the side of the nappy to wee, this works best sat on a toilet because of the angle and can allow you to wee in a toilet without undoing or removing anything and without having to refit the nappy after. If this isn't quite enough space you can just undo the bottom tap on one side or even both tapes on the side if needed and then tape it back up after, if doing this it's best to alternate which side you use.
The other option with tapes is to put it on just a little bit loose, tight enough to hold it up and prevent gaps to leak from but loose enough that you can just pull it down like underpants to use the toilet and then pull it back up, it can take a bit of readjusting to get it to sit right again (can give tips there if needed) but this can work if for example; you need to go no. 2 and want to use a toilet.
As for plastic pants I do recommend them for side sleepers and as
@Bigbabybret said, wearing some briefs (or better yet boxers) between the nappy and the plastic pants to soak any leaks is the easiest way to handle it if you can't find a nappy that works for you, but taped nappies will be much better here than belted anyway so may not be needed.
The best option for side sleepers who struggle with leaks is actually to use cloth nappies (flats, prefolds or fitted/AIO, but not pockets) because their absorbency covers all around, crotch, bum and sides so that when you are sleeping on your side any wee that falls to the side of the nappy still can be absorbed where disposables just have the thin non absorbent wings. The downside to this is needing to wash and dry them.