Back in the heyday, Hunter only applied Petit Trinidad to the bottom but really for a clean lake it was not necessary. As for trailerable sailboats without staying in the water except for a few days, I do not recommend it other than to wash off particularly coming out of zebra musscle infested lakes up north. I use to apply West Marine CCP which was designed to be effective if out of the water for example the winter and still goood for the following season.
As for bottom painting, there are many approaches but most will concur with me on metal keels, brush to a clean surface, apply metal primer which is basically zinc chromate under differeent names to prevent rusting, fill in the holes with two part epoxy and the best I found was Water Tite. Sand smooth and then prep the rest of the hull and paint with anti fouling.
After several layers, then the paint needs to be removed. If flaked off in many areas, then take all of the paint off. When a new or clean hull ready for antifouling, two coats is recommended with a third coat around the water line.
crazy dave condon