This rivet nut is the best option I found so far
Maybe wiggle one of these in there and use glue to hold them to the back of the sheet metal?
Update 12/14:
I tried to make 20466 fit but it didn't (video)
Why would you not drill holes so that they are actually strong? Slotting into these will yield a weaker mount point 100% of the time versus a correct-sized hole drilled.