[Tim Brewer]

I'm not a paint expert, but the paint guys are right. The gel coat is not something you stay with. It really is only there as a release so the body won't stick to the mold. The ONLY right way is to drop the $$ and have it painted. The gel coat is not always evenly applied and when sanded can easily wear through to the glass. Long story short, you don't wont to do what you're thinking of doing.
Tim