What size Boat is it?
What you could do is this.. Put something under the Stern on the port and
starboard corners. build up some block of wood.. or if tall enough 55gal drums
with carpet to protect the gel coat. Then find someway to lift the bow of the
boat in the air. a H frame with apully? and put the keel of the bow on a
Block of wood after you get the trailer out from under it..
You can stablize it more about midship with two more barrel.. which if its a
big boat would be a good idea to begin with before you put it on the keel. Done
it like this for year and it holds up durning the earthquakes we get up here in
washington state from time to time. Cali. might be a whole different story.