I just had some experiences with a steep ramp here on the Cape. We did a simple trick that works like a charm.
We've got a Load-Rite roller trailer, and an F-350 dually.
First, back the trailer in as far as you desire. Our truck's rear tires were wet, but the water wasn't up to the wheels themselves. The back 1/3 of the hull was in the water.
Second, run a line from the starboard midship cleat up to the bow cleat, but just run it through the hole in the cleat, don't tie/wrap it off. Take the bitter end of that line and run it from the bow down to the trailer post (where the winch is).
Third, tie an alpine butterfly in the line, between the bow and the post. Tie a slipknot through the bight of the butterfly, and toss the bitter end onto the bow.
Fourth, slack off the trailer winch, letting the line take the strain. Disconnect the bow eye. and safety chain.
Fifth, hop onto the boat bring the bitter end of the line down to the console, and when you are ready, pull it. That'll pop the slip knot, and the boat will slide down the trailer into the water.
Finally, pull the now-untied line back aboard from the midship cleat. Now you are in the water, with no trailing lines. Voila! Go dock the boat and move your truck/trailer.
This works if you can get aboard the boat from the dock next to the ramp. If you can't, just tie the line right before you back down the ramp. I'd put a rear safety line on in that case, another slip knotted butterfly from the transom to the trailer. Just pop the aft one once you are down the ramp, then the forward one. Its incredibly easy, and I always chuckle when I see people trying all sorts of crazy schemes to launch alone. I've seen more boats dumped at the ramp, or launched into the channel than I care to remember.
We usually have two people, but this is very doable with one. Just make sure to tie the slip knot with a LONG loop, so any slippage won't result in the boat falling off the trailer.
