Here is what I could put together regarding the installation on my "Jim Fisher" RS-15.

It looks like either a tow-hook removed from another glider or a tow-hook assembly purchased somewhere. In either case it has been adapted well to the RS. In photo one you can see what it looks like on the bottom of the fuse. The round ring and retaining finger is contained in a stainless steel housing that is shaped somewhat like a convex iron (as used to press your shirts). The rear edge of this plate is precisely at the front opening for the landing gear. The SS plate has been glassed onto (into?) the fuse and protrudes an eighth inch or so. It would probably make a good skid for a gear up landing.

Photo two was taken looking down into the cockpit rear, the parachute cushion is pulled forward to expose the CG hook hardware. You can see the 1/8" thick steel straps that help secure the hook to the fuse. The bent strap that protrudes forward protects the release mechanism that is cable actuated from the left side of the dashboard (nose hook release is on the right). While this protrusion looks like it could be uncomfortable to the small of one’s back, in practice the thickness of the parachute or seat back cushion and the posterior cushions make its presence undetectable.

Not pictured here because it is buried up into the landing gear area is where I strongly suspect the tow-hook assembly is fastened for greatest strength. I believe it is fastened to the top of the pivot of the front arm for the landing gear. That part is enclosed in an aluminum cover so I can’t see without some disassembly, but I think you get the idea.

I know the tow hook works because there are many winch launch entries in the logbook that came with the glider.