Joh,
There actually IS another option, if you're dead set against wearing Depends.
You can order a drysuit with a "relief zipper". It's essentially a short horizontal zipper that fits across your abdomen, above the crotch of the suit. It looks like this:
http://www.altrec.com/shop/detail/19763/NRS/
(Note that I'm not recommending that drysuit, I simply wanted a photo that showed a relief zipper...)
On the boat during the surface interval, you pop that sucker open and then use one of these little beauties:
http://www.travelmateinfo.com/page002.html
Presto, you're feeling 300% better and you don't have to break your seals, strip down to your undies, etc.
Some folks will comment that the relief zipper is another failure point. That's true to some extent, however the relief and convenience that it provides may be enough to offset the requirement to check that its securely zipped before each dive, well-maintained after each dive, etc.
It's a least another option for you to consider rather than the Depends.
Best,
Doc