epoxy over polyester is fine...polyester over epoxy doesn't work...gelcoat is polyester so you may want to rethink your bottom coating or have the work done professionally...kevlar is hard to patch due to the inability to grind it ( tendancy to fuzz) and also it does not wick up resin like fiberglass does...if it was up to me i would repair with epoxy and urethane the entire boat...sure paints are not as abrasion resistant as gel, but in terms of weight savings are advantageous