I recently read about that Miracle paint, seemed like a good product for cheap. I was thinking of using it on a box truck I was doing. I ended up using the "cheaper" Miracle, not the implement paint with the hardener. It didn't work well at all. For the sake of saving $30 it was a mistake. I've used SEM corrosion preventer inside panels. It leaves an oily/waxy coating and seeps into crevices to shield the inner panels from moisture. I use it inside rockers after I replace them and inside quarter panels where I can't get to weld seams after the panel is on. Also good for protecting the hem on the bottom of doors and tailgates. You can also use a zinc or chromate based primer if you want. I'd weld up the holes, then go in through the tail light and spray it. If you have a good amount of access you can even try hitting the rust with a converter first, if the rust is substantial. Do NOT spray undercoating directly on rust or bare metal, it will trap moisture and accelerate the rust! If you have a good amount of access, prime it and paint it. If access is limited go with the SEM corrosion preventer. You can get it in a spray can with a red straw or they also sell an 18" wand attachment for the can. It also comes in qts. that you spray with a Shutz gun with a 360 wand attachment, if you want to get inside rocker panels or other areas with no access.
to help neutralize any possible rust? As I'm writing this I just realized I can probably access the inner panel by removing the tail light.
