fiberglass floor pans

That may be the silliest thing I ever heard. Floor pans are cheap, man. Or as someone said, buy some sheet metal and make your own. Or go steal a stop sign like we did when we were kids and weld it in. It makes no sense to do a flimsy, half assed, unsafe repair only to have to do it again later when you have the money to do it right. Assuming you lived through the first repair.