Hi,
I'm using RivNuts to hold some things to the ribs and frames.
I install them with this thing:
[ame]http://www.amazon.com/Astro-Pneumatic-Tool-1442-Riveter/dp/B003TODXQW/ref=sr_1_3?ie=UTF8&qid=1409517272&sr=8-3&keywords=rivnut[/ame]
The rivnuts look like this:
[ame]http://www.amazon.com/Ribbed-Series-Rivet-Nuts-Steel-Yellow/dp/B008VGVC5C/ref=sr_1_16?ie=UTF8&qid=1409517272&sr=8-16&keywords=rivnut[/ame]
They go into hole in the frame that is just the right size, and the puller expands the back of the rivnut to lock it in place in the hole.
Then a screw with thread that matches the rivnut just screws into it.
Easy to remove the screw and reinstall it any time you want.
Not sure this is the best way to do wall panels, but I guess it would work. It would require placing the wall panel against the frames and ribs, drilling pilot holes wherever you want a rivnut, then pulling the panel away, then drilling out all the holes in the frame to the rivnut size, then pulling the rivnuts with the puller, then putting the panel back in place -- lots of steps.
The few I've used do appear to hold well.
Gary