You might drill a hole in e piece of steel and tack weld a nut on the other side of the hole.
The piece of steel is supposed to be almost the same size as the hole in the frame to be fairly thick and substantial. If you weld a nut, it won't be able to fit through the hole in the frame.
I have zero ability to weld, sadly
I’d likely just try to recreate what Ironman, ARB, and others have done with what piece of metal and just tap/thread it. But I’m trying to avoid that effort if only someone would sell me those bits![]()
Please let me know if you find someone that'll sell these pieces. So far I've tried with the ARB vendors without success. I'm getting ready to recreate the ARB ones by 3D printing a plastic set and having a metal fabricator make them.