Re: remote winch hook release ???
I used to self launch a 26' Welcraft Coastal but I am older now and don't move so good.
I now have a set up for self launching which may help and is not complicated for my current boat, a 22' catamaran Dual Console bowrider. This boat also sits very high, about 7' over the trailer tongue. However it does have a ladder on the winch stand. (Which can be aftermarket fabricated).
I mounted an eye bolt, heavy duty and welded closed,facing to the rear of the trailer, in place of the top mounting bolt for the winch. I also fabricated a line sufficiently heavy to hold the weight of my boat, 4500lbs, with a heavy, open ended hook, on one end, about 6' long. Length can be adjusted to your needs.
When I get to the launch site, during the prep process, I attach the hook to the eye bolt, open end facing up, and tie it off to a forward cleat.
Upon backing in to the water, I release the trailer hook, at which time the "launch hook" then takes up the load. I climb into the boat, (this has to be a funny sight), start the engines and when ready to release, I untie the cleated line, the weight of the hook drops the end off the eye, I pull the line onto the boat and I am good to go.
When loading I reverse the process, catching the hook in the eye, tie off, climb down, (another funny sight), attach the trailer hook and winch it tight.
This works very well for me, and I even use it when launching with the wife so she doesn't have to deal with the winch.
However, I think you are going to have a problem self launching in any manner other than with guide ropes as you have a roller trailer.
The biggest factor in permitting any on board self launch would be the friction of the bunks, giving the self launcher the time to release and reposition at the helm before sliding into the water.
I can envision some very interesting mad scrambling trying to get to the helm of a boat rapidly sliding down the trailer and shooting off the end.
Some changes could be made to the trailer, but that would defeat the purpose of a roller trailer.