My car's body was reassembled many years ago with bits from Moss and TRF. I am struggling to put on the sealer plates ( from Moss). I have riveted Captive nuts to match the holes in the plate, but on the passenger side there is not enough body sticking out and I will have to use self-tapping/sheet metal screws. The perceived problem is how to fill the space under the sealing plate and around the top edge so that water (and rust ) do not get trapped there. It will not be a very snug fit. Advice needed! Pics will follow tight, I hope.