Hello everyone,
I know this is an older discussion here, I just wanted to point out that there are other tools for this too.
I needed a tool for setting rivet nuts in very tight spaces in my small vintage camper.
The lever arm solutions that I only knew before didn't work for me.
I now have a "GOEBEL GO-12-N" (there are also similar ratchet solutions from other manufacturers, I was looking for one that had spare parts and other accessories and a wide range also for useable for stainless steel nuts), for M5 to M12 (my photo with M6) and optionally also for smaller M3 & M4 rivet nuts - It only requires a small amount of force, has easy-grip lever arms, ratchet-like, even in a small installation space usable for me less than 90 degrees working angle and only 21cm tool height. It's fun to work with it, I think I'll be getting a lot more rivet nuts soon...
I had previously tried it cheaply with screws, nuts, washers and 2 wrenches - with lousy success.

regards,