The holes are that small you could just mig weld them, but you will be ok to just lightly tap the holes in, then fibreglass rub rub!! then filler or stopper, prime and paint, and dont forget to paint behind the repair so as no condensation can creep in from behind, theres nothing wrong with fibreglass if used correctly, A recent test by practical classics, who first drilled large holes in a panel then subjected it to salt spray for ages, and it held up perfectly, Ive used it for years and never had a prob or comeback! dont be scared! Ant!