Where I live the water is deadly cold. So, I use a sea sock and floatation bags. Without the sea sock, LOTS of water gets in the boat if you have to wet exit. It still floats with the air bags installed, but not particularly well.

So, that's what I recommend if you are getting away from shore. I still recommend a sea sock, in any case, as it also keeps sand and grit from getting in the boat.

As for bulkheads, yes, people have installed them in SOF kayaks, and they apparently work OK. You can find articles on making them, and how to make your own sea sock at the qajaqusa.org site. Check back articles of the "Masik" newsletter for the sea sock, and search the forum for the bulkheads.

Good luck!
Dave