I had the same issue on an older fiberglass cobra and solved it by
taking to an auto repair shop. Had to hunt around a bit before I
found one that would take it. They sanded and filled as needed and
then primed and final coat as though was a car repair. Even put it
through their drying/curing hot room. Came out very nice and much
less expense than if I would have done it myself. Suggest looking
into that kind of repair.

ASW27BV