Air Punch Flange Tool

and here I thought I had my decision made. I don't know how to weld yet and was going to get someone where I work to spot weld the panels. I don't know if I can convince them to spend that many hours on 4 panels, front and back of the rear wheels. $1000 plus freight is not in the budget for full AMD panels. Partial panels are still $600 plus a lot of welding time. But on the otherhand, I don't want rust a year from now. There must be a way to do the job right removing any future potential rust issue. If I punch holes, use weldable primer on both panels, spot weld and putty, put seam sealer on the back, plus undercoat, shouldn't that take care of the potential rust issue? I live near Washington, MO