Suggestion. Tie a USCG approved pfd to the boat; one for each passenger. The little co2 waste packs are pretty lightweight. Better yet, wear it on your waist.
I can't sail without wearing mine.
But Gary, I think you've found a loophole that mirrors the throwables. I commend you for your creativity.
The only catch to that I think would be when they require you to actually wear the PFD. Don't they fly a specific flag?
Like I stated; I wear mine. I just can't push the envelope if I don't have it on. And when I hit the water, I just wait to get popped to the surface.