I just got a new onesie from AdultClothDiaper that is very much improved.
In all of the ones I've found before the snaps have been the weak spot. No matter how careful I am, the eventually pull out of the cloth. In some they weren't even set properly in the hem.
This one has them set in a strip of rugged fabric, which should last as long as the rest of the shirt. I've got a half dozen old ones that have been waiting for me to do something like this to reset the snaps.
ACD Coverup Adult Onesie
Here are a couple of snapshots:
Unfortunately for you ABs, they only come only in white, dark blue or kahki. On the other hand, they're discrete if you're wearing them in public.
Kudos to ACD.