Well, no...but now that you mentioned it....!

I know someone that did that with a Gortex dry suit but without a life jacket and they practically had to walk with their hands on the bottom until he could get to shallower water - bending to come up for air occasionally.

If your legs and feet are totally inflated, you cannot get your legs far enough below the surface to let the air travel inside your suit past your waist to your upper body.