Hey there skunk,
I have the same problem... I fractured 2 vertebrae , right dead center of my back, when I was in the 82 ABN Div. I have no idea how much $'s I've spent on seats basically trying to get out cheap. Finally I bought the Tempress Navistyle seat at BPS. ($99). At the time they didn't have the Hi-Back version. I ended up buying the Hi-Back this year for my one-man boat but I actually prefer the low-back better. I truly wish you the best with your back, and I wish I could be of more help.
I actually took a car seat, from a Chevy Cavalier, (because you can recline those seats) modified it , put it in my Bass Hunter, but it looked like I was sitting on a big ol' throne so i canned that idea.