I’ve also worked quite a bit on the inside of the compartment where the fuel tank goes. I replaced all the rusted out metal on the outside of the body. The inside lower sections all were pitted and had some pinholes. I decided rather than cut it out and replace with new metal - I would add a layer of new metal to the inside. I cut and fit several pieces. I did the sides first with each having a lower lip and then I cut a floor piece and installed it so the side lips hold it in position. I used 3M body panel adhesive to install all this. Seems very strong - the original metal may continue to rust a bit but there is plenty of new material that should last. That looked pretty messy but I wasn’t done. After letting it cure for a week I went over everything with a 2 part white liner product. (T-Rex; it was fairly cheap and I could buy a single batch - one bottle of liner and one bottle of activator). Rolled and brushed it on. I think it looks pretty darn good now. I plan to clean and wire brush the outside surfaces and coat them with a black liner material. Should last a long time I think.