Back when I was asking about this, as you see, no feedback at the time. Somebody mentioned another rust dissolver product in another thread about this time called RUST911. It arrives as a single gallon but it is concentrated to make 16 gallons from it. I ended up making a tub out of plywood and layers of heavy plastic sheeting. It took about 20 gallons to fully immerse the hood with what I made. It worked AMAZING! The vendor also sells a Metal Shield that can be sprayed on for flash rusting. It easily cleans off with thinner for painting. I've only moved into the primer stage so I cannot vouch for longevity yet but I see nothing growing back when I look inside. I did treat the inside with some older epoxy sealer from another job. I taped off the edges and rolled the hood around to work it into the seams.
Pictures of the dissolver in action after about 15 minutes show the clear water-like dissolver looking like a cloud of smoke billowing out as it worked on the rust. Overnight and the inside was smooth, bare metal.
