for a flat bottom dory.....I would guess it would be a simple matter to customize a utility or snowmobile trailer for your use. I've seen teflon slides used to get the dory on & off. A small manual winch would be good for tougher (steeper) launch sites. How heavy is the boat ....500-600 lbs?
Good luck & keep us posted.
ps. If you'd like me to come out to Vail for a fish & ski (and technical advice)
could make that work .... he he he!