I met a guy once who was involved in one of the old "Little America's Cup campaigns. Instead of hooks, they used a system just like seatbelts from cars/airplanes. It was the old style, with a big lever style unbuckling it - not the pushbutton kind we have today.

What do you think about that kind of idea? Would just be a small stainless square tab thing on the boat, and a buckle on your trapeze harness. Un-hooking would mean just reaching down under the buckle, and pulling up on the small handle mechancism. No hooks or anything.