Hi Bmedlin85....
i did our jet boat seats.. came out pretty good once you get them out, old material and debri off, pull out a bazillion staples...
that was the hard part i think. getting to the bolts wasnt really that bad, more awkward and physically painful--hanging down from seat back, head in engine compartment.... anyway, it went well. the heat gun part, though i didnt use one since its so hot here and the material was already loose and stretchy. the seat bottom and seat bottom cushions came out fine and good enough for me; although, if i decide to ever do it again, i would probably USE a heat source to stretch more of the fabric to stave off as much wrinkling around corners as i could.
that said and done, our seat back rests were pretty much fine as they were, but i could see the odd shapes posing a problem.
but they DO sell material KITS, all pre cut and shaped for all the seat parts.
source of material--marine vinyl, i went to joannes.. great selection and prices were fantastic!! GET COUPON for half off material!! they can be found on their website or other coupon site.
how much fabric... well... i just measured the seats across and front to back, and doulbed it for sake of wrapping under for stapling as well as leaving room for the shape and strecting. all in all, cost me under 30 dollars for material to do entire bottom.