Back in the early 80s I bought a 77 Chevy 4x4 that was much rustier than my TJ. The rocker panels were gone. I called my brother in law in Nevada and had him cut the rockers, cab corners, part of the floor boards, and front door pilers to the bottom hinge from a junkyard out there.
Not knowing much about body work, cut the rust off my cab and brazed the clean rockers on.
I know brazing isn't used for that purpose nowadays, but my body work turned out pretty good, and lasted longer than the originals.
I still have my torches. I may have to pick up some brazing rod.
