[Ronbo]

Although it's not relevent to this application, in a blind hole situation use well nuts if possible. Always isolate with rubber to prevent vibration shock being transferred to the fiberglass substrate.

Big problem with fiberglass is the gelcoat / paint surface is far more rigid than the fiberglass underlayment.

BTW carbide burrs are the best thing I've ever used to drill into glass, the more cutting edges the better.