Last year I painted the bottom of my Oday 22 on the trailer.
I sanded most of the bottom with the boat just sitting on the trailer.
I painted one side at a time by jacking the trailer one side at a time, braced the boat under the rubrail, removed the tire, lowered the trailer until the bunks parted from the hull. Then blocked the trailer and removed the bunks. The stands for the bunks are bolted onto the trailer so they were easily removed.
It was a pain working over and around the trailer.
Sorry, I don't have any photos of the process.