this might have been covered already and I missed it, apologies if I have.
Returning to the thoughts on flotation options the current method is sponson mounted inflatable floats as standard and they seem perfectly adequate providing the ditching is relatively textbook along with kind seas.
I think I saw someone mention high floats on a wasp meaning that you would be underwater with potentially a still spinning disc to emerge into....!
As I say this may have been mentioned already but would it not be logical to have a float mounted somewhere high up on the side of the main door? My thinking being that if the ditching is a good one it would not be needed, however if you have a ditching like this one, or the sea state is not at all helpful then it will at least keep one side up, preferably the one with the big door allowing more time for escape and a reduced chance of drowning in the process.