no matter what you do, whether it's a pre-formed patch panel, or you fab a patch yourself out of sheetmetal, rule #1 is REMOVE ALL RUST! If you weld a patch over top of old metal, you just create a inaccesable area for dirt,water, and any other debris to get stuck, and then after a few years you're back in the same boat. Here in Minnesota, I've seen cut rate body work last as little as a couple years, and it's right back to rust again.
