Its possible to remove the rear quarter panel,its crimped on to the subrail.I fixed my rear body mount bolt holes by welding the cracks,grinding flush and bridging the work with a piece of flatbar,you can see the repair at the center of the fender well.If you do pull the quarters be aware as John said jigging and squaring is necessary
JRN67,if that's a 31 sport coupe its a low production car,it was the hottest car on the market at A introduction,134000 in '29,by 31 production dwindled to 19k...only 6k in '32..from an economic standpoint I agree with you,buying all the wood,brackets,padding and top is close to 3k..