Yes, mr_velocity is quite right...
Any flotation in a canopy/enclosed boat is very bad. Yes a Switlik is good also we make an AirVest for canopy boats. Go to this link to view more. http://www.benhedrick.com/srp-lifejkt.htm
In the event of being upside down you will have to swim down to go up, and any flotation will make this nearly impossible.
Thanks and great write up, I too have driven and race several of the Bat Boats, quite the ride.
Take care, Ben