A co-worker of mine said that in buffalo where his in-laws sail they use a small tractor to haul the boats to the water. I would guess they just drag the trailers to the water. Somebody on this list probably sails at that beach.
You could probably find an old riding lawn mower with 15HP cheap.
I know it is tuff even with the slight grade on our beach. My prindle 18 is only 300 lbs and I can move it easily on my own, but the guys with the Hobie 18s… I always run over to help push. That extra 100 lbs makes such a big difference.
Matt