I just removed the paint from the fin of a plane without damage to the fiberglass underneath using Floquil Polly S Brand "Easy Lift Off". It is available at some better stocked Hobby shops - especially ones that cater to model train folk. It is non volitile, odorless, and doesn't attack fiberglass, epoxy, plastic, etc. Good stuff - a bit messy and time consuming but worked great.

Good luck,
Eric