Single wall on a double wall bed

[k-nuts]

What about weld nuts under the bedrail and slot the fiberglass top a bit. Washers on the bolts would hide the slot and hold it tight. Seems easier that repro-ing the moveable cage nuts. Mine has holes for the double and I got it with a single. It too was only bolted at the windshield and the back. It squeaked like crazy driving it home. Been topless ever since. (in my garage waiting in line for resto)