[TheSilentChamber]

Cut out the area thats rusted and prep it with a wire wheel, weld in the patch panel that is the same thickness as the surrounding area, no point in going thicker, dont use stainless use mild steel with a high carbon content, as thats what the car is made of. Your not going to be able to use an arc to well stuff that thin, your going to need a MIG or TIG, tack weld little spots about 4" appart and cool it with compressed air and work your way around till its one solid bead. If you run one continus bead it will warp it. grind the welds flush, paint. You can use rust preventive if you want but if you prep it and paint it properly you wont need it.