Lifting Boat on Trailer
First, have the trailer on a very level spot, block the wheels, then raise the hull with a small hydraulic jack placed close to the transom along the keel line. (/this requires having a lot of spare blocks on hand to get to right height.) Place 4 x 4 blocks (padded with carpet or cardboard and about a foot long) between bunks and hull. Then raise the front with the jack along the keel line, and block forward. Be sure everything is very secure before working beneath the hull. Also I've read that you can tie your blocks onto the empty trailer when boat is in water, then float boat onto them and pull the trailer out with the boat at the higher level. Seems like it would work well, presuming that you can do your paint job at the launch area. Either way you will have to move the blocks once, to paint where they were the first time.