It’s a tough spot to work on. I figured if I could get the outer skin looking good the inner side doesn’t matter as much. My car is going to be a driver not a trailer queen. I basically poured rust converter down inside after scraping away all of the loose rust.I'm trying to figure out how to tackle the rust in the trunk lid.. Its down at the seam and would be really hard to fab up. I was thinking of hitting it with rust killer and seam sealer. I think the fabrication is beyond my abilities. However I have pulled off some weird stuff before.