Instead of the main sheet to raise a person, you might be able to use a adjustable trap to lift someone high enough to pull them on board. At least they would be attached to the boat.

The tethers may be needed at night, but I have visions of Peter Panning at good speed and having that tether pull up tight before I hit the water. We stuffed it one time and when I came up I was at the end of my trap wire above the mast. We flew about 50 feet thru the air. I'm not sure I want that tether stopping me at 25 feet. My harness has a spring clip on the hook that keeps the dog bone attached to me....At least so far.

The crew should at least be able to stop the boat by themselves.