15" would be easy, and I'd guess about $300. The mechanism to lift 15" would store easily on the trailer, and the stress & stability would be easily manageable. I would do this job by using a pair of (removable) inverted A-Frame side crank trailer tongue jacks, attached to the side guides on the trailer, and with a special machined foot (now the top) that would fit the contour of the underside of the gunnel. For the third lifting mount, I would run the front trailer winch strap up to a roller mounted on the mast support post, and run the strap up to the roller, and back down to the bow eye. I estimate about 150# load on the front strap, and about 600# on each 2000# capacity A-Frame jack. It would be quickest to raise the boat with 3 people, but one person could raise each jack in increments until the boat reaches the desired height. More than 15", the price goes up. I could probably package 24", but I think you would be looking at $600 plus. And I think that with 15", you can clean the bulb, then lower the bulb to the trailer and get the part of the keel in the trunk.