Auto body repair & detailing: hinge repair, seam sealer, door hinge

Question
I'm working a 1987 caravan installing a backer plate behind driver door hinge.Should I use galvanized 14 gauge plate or use weldable primer? Also what product to use on refilling the seam in that area it's grey to light tan when grinding it. Also why are the chain paint shops so cheap are they okay for just painting this vehicle? I've pulled all the mouldings and hardware off should be very little body work to do.     Thanks Tony

Answer
You have an 87 Caravan that has very little cash value, do not go overboard with an expensive paint shop. Use 22 or 24 gauge metal for a patch or backer plate. Seam sealer is a matter of preference. Latex household caulk works fine and does not have the automotive price tag. Prime the area first before you caulk though.