I admire the craft man ship 100%, but you are putting a band aid (thin piece of sheet metal) over a gash that needs stitches. The underlying rust with oxides the new panel, creating the same hole as that is the source of this chemical reaction. I’d would replace the fender/ ass end of the box panel with thick steel, and powder coat it to color match the paint of the truck. Again, Im not hating and I fully admire the craftsmanship and time and effort but this won’t solve the rust problem.
I admire the craft man ship 100%, but you are putting a band aid (thin piece of sheet metal) over a gash that needs stitches. The underlying rust with oxides the new panel, creating the same hole as that is the source of this chemical reaction. I’d would replace the fender/ ass end of the box panel with thick steel, and powder coat it to color match the paint of the truck. Again, Im not hating and I fully admire the craftsmanship and time and effort but this won’t solve the rust problem.