kook - I guess the easy answer is increase the size ( diameter ) of the latch pins. Make sure to increase the strength of the front brace of the seat and the area of the bolster support that the pins go into.
Have upholstry shop add 1 1/2", closed cell foam ( the real expensive stuff ) on top of your existing padding. They can create a seam on the additional vinyl material near the bottom. It will not be that obvious.
Another option may be to call Sunsation and order a driver side footrest. When I am running hard in rough water, in the seated position, I place my feet on the angled footrest. When I see a hole, a big wave or an " oh **** " situation, I push up slightly with my feet. This takes the pressure off my butt, seat & back.
Most race boats have specially designed , padded and secure seats. These seats insure that the operators bodies stay in one protected place. It is difficult to contro the wheel, throttles, tabs and trim when your body is being banged around. Godd Luck Paul
See Ya in Annapolis!