Does fiberglass resin react to battery acid?
I've never actually poured battery acid on fiberglass, but I used to make fiberglass exhaust systems for evacuating acid fumes from computer manufacturing facilities.
The acids used are REALLY nasty in those places. Hydrofluoric is quite common.
I would bet it would work fine as long as the actual glass fibers weren't exposed. A good gel coat between the fumes/spill and the fibers should do the trick. The nice thing about fiberglass as opposed to PVC is it's very tough, will take a beating, and can be formed to any odd shape.
Frank D.