I had a Precision 23 years ago and painted the bottom on the trailer. It sat on the keel/centerbard trunk, keel rollers and bunks under hull on each side of the rollers. I ran a line from each of the cabin top winches to each side of the trailer frame to keep it from tipping, then used a floor jack with 2 x 6 (to spread the load) under the stern to jack it up about 10". I blocked it in a few places for safety, then sanded, painted, let it dry and lowered it. Used the jack to lift the bow a little to paint above the front rollers. I used plastic to keep paint sheeting off the bunks and trailer frame. Two coats of Trinidad lasted 3 years in the slip. I did remove the outboard, gas tank and drained water tank before lifting. Seems like it took just one Saturday start to finish. I got the idea from a sailing buddy who used to do his Chrysler 22 that way. Saved a nice chunk of change.