[DanEC]

Fiberglass can be repaired just fine without showing through the paint over time. If it couldn't you wouldn't see a 53 - 82 Corvette that didn't look like crap because almost all of them have been banged up and repaired over time. It just takes doing the repairs properly, using resins that are compatible with the original resins and fiberglass mat and not cloth. Plastic filler is not a proper body "repair" material although it's just fine for panel smoothing. I restored a 66 Corvette 25 years ago and did all the body work including replacing a rear quarter panel and glassing in all the original body seams - The front clip had been replace earlier. Even with lacquer paint I sprayed on it you can't find a repair anywhere on the surface 25 years later.