I just finished doing the bottom of my 22' Angler. It went something like this.
Place the trailer on a concrete/paved driveway and anchor the boat stern to a tree or other anchor. Pull the trailer foward 1 foot. Stop
Using a floor jack and 4 x 4 block of wood, jack the boat up and block the corners. Pull the trailer out being sure to not go too far, keeping the nose on the trailer.
Lay out plastic drop clothers and prep the bottom for paint, masking, sanding , etc...prime (?) , paint the bottom and let dry according to your paint choice instructions.
Back the trailer back to the blocks...jack the boat up, remove blocking, let the boat down....Finish painting the blocked/trailer resting areas that you were not able to paint before.
Take to nearest ramp and float it the rest of the way on...or just going boating.
It takes two people to get this job done...stock up on refreshments and take your time. Moving the trailer around on payment is so much eaiser then doing it on a gravel drive or sodded lot like I did.
Plan "B"...have the local boat yard block it and when you have the bottom done...put back on the trailer. Plan "B" cost a bit more but takes a lot of the pain out of the process.
Good Luck