If your -really- inclined, my brother used to have one boat and two trailers, and would always be swappin em around for some reason or another.
What he did(being a scaffold erector) is build some scaffold around the trailer about two frame high and toss 2 I-beams on top. Then he'd take a couple come alongs and hook em to the eye bolt at the bow of the boat and toss a recovery strap underneath the stern, hook that to a come along and winch the thing up.
Sure you could use the same thing, but a little simpler for pullin boat moters. Might be easier, or not. Just tossin some ideas out there
