Ever seen the big overhead gantry cranes that run on railroad tracks, like at container ports and rail yards?
Antelope Valet Ramp has those high walls that could support a similar system. Drive the trailer as close to the water as possible, then have a mobile gantry type crane sling the boat, carry the boat to deep water, and then float the boat out of the sling and away. I'm no engineer, but Antelope doesn't have the luxury of extending any of their ramps by another 1/4 mie to chase the water, like