I too fly fish out of a v-boat - tube - I also now own an OK Prowler 13.
To fly fish out of it is really easy. All I do sit cross saddle- that’s both my feet - (in waders its cold out here in the UK) over the one side.
I normally fish a 10-6" Mieser switch. By sitting sideways with my back resting on the seat - I can strip the line into the leg wells. No hang up's - long or short casting comes easy.
Doing over head casting helps, Saves fanning around double hauling all day.
Stability - No problem –even in rougher water fishing like this - the Prowler is a really stable yak - plus its dry - has a slightly higher centre of gravity than most yaks. Mine doesn’t have a rudder, but with a sock - you can control you drift well over most situations.
Yak Fishing is taking off in this country - soon there will be a small flotilla heading out every weekend.