[jr_ss]

Theoretically, he could just drill a couple pilot holes at the 4 corners of the nut and weld through the sheet metal to the nut. It’ll serve the same purpose as having access to the backside without cutting a huge hole. Put the bolt in from the opposite side of you can, thread the “captured” nut on the outside and mark where you need to drill. Reverse order and a few hits with a mig and you’re done...