I back up to a stout tree, couple of hefty ropes through the stern eyes around the tree, jack up the transom at the keel to get the hull off the bunks. Block her at the chines, then start pulling forward to where I want to block her fwd of midships. Remember, a good 75% of a boats weight is from the console aft, so I'll block her about 3' fwd of the console. Jack up the keel again, block the keel, and yank the trailer out.