I recently spend 16 hours removing/sanding off paint from my hulls in order to be able to do a bottom job on mine. Don't use paint, you'll just suffer later when it's time to do your next bottom job.
Paint will wear out on the beach much quicker than gelcoat. At the marine store I bought my supplies, a quart of marine paint was a few bucks more than gelcoat, so it was a no brainer. I don't know if the salesman knows his stuff or not, but he was telling me that top coat paint is not to be used below the water line because it's not waterproof (just very water resistant) and that it would eventually blister, expose the fiberglass, which means I'd have to repair it again sooner rather than later.
1978 Hobie 16 Keoke, sail# 36 84