That's a neat idea. I don't know if I would want to sleep on that bed though. I'll be diaper poor after this weekend. I get two packs of Tena Slip Maxis today and two packs of
Attends Waistband Sat or Monday. Plus all the other diapers I have on hand. It wouldn't hold all of my diapers.
Sorry the first place anyone looking will look after the underwear draw is under the bed.
This would work as long as people didn't know it did that. Beds that have a solid frame all the way to the floor like this usually have drawers in it though, so if you cut through the front and build a couple semi small drawers into it, then nobody would think anything suspicious.
My only fear would be if you had painters come and move the bed or movers...
I use a large safe and i hide they the key and label it as a shed tool cupboard key.
The best places are places where no one would ever hide anything, no one has reason to access, and can still keep a stash hidden in the event someone accesses the hiding spot. For example, a box in a storage area with a decoy label and some decoy items that match the label placed in the top of it. The box would be extremely unlikely to be moved, in the event it was moved, it probably wouldn't be opened, and in the event it was opened, a cursory glance would reveal the decoy items on the top layer match the label and there's no reason to investigate further.
I have a bed a lot like that and a king size mattress weighs a ton even with the helper pistons on the side which makes it very difficult to lift. Right now it keeps 3 bags of Abena's, several guns and my wife's wedding dress. Granted we have a very fancy mattress but my wife can't get in there without some help. Its not really about being a good hiding spot necessarily, its more about who is going to be digging through your stuff to the degree that they find and manage to lift your mattress. For example, I don't think that hiding spot will go unnoticed by a burglar but when we have guests I'm pretty sure they won't be looking under my mattress.
My house also has a secret room. I highly suggest the secret room if you can manage it. Think less James Bond and more dusty cellar though. Its not a hidden sex den but it does supply access to most of the utilities in my house and its where I keep my safes.