Jim, We camp near the ocean - A LOT ! All of our stuff, RV's, TV's, Bikes etc. rust worse then your chassis and we have to keep after it. I had my last TV Ziebarted. My last TT was really rusted and it was only 3 years old. Anyway, the easiest way I have found to solve or fight the rust is Rust Oleum rust coverter (black) in a spray can. This product coverts the iron oxide into a primered paintable surface. Looking at your frame it looks like all you will need to do is spray it on, right over the rust. If your have any loose rust wire brush or scrape just where needed prior to spraying. I think you caught it in time where you can have your entire chassis converted in one day. Wear a respirator and you may want to purchase a plastic handle/trigger for the sray cans to save your index finger. I found the converter is least expensive at Wallmart. I would get 10 cans and take back what you don't use. Also, you'll want to purchase a black finish coat (semi gloss) in spray cans at the same time. A friend of mine purchased a BH 3670RL in March 2010, took it to the beach and spent the first week repainting his entire chassis with a brush even before it rusted. He, like me, knew it would rust so he beat the rust.