Best method to restore rusted metal?

POR-15 needs to be painted as it is not UV resistant (says so right in their lit and website). If you use Rustoleum Stops Rust, bear in mind that a wire brushing is likely all you need. It works best with a light amount of surface rust. Since rust is simply metal oxidizing, you need to stop the air/water from reaching the surface of the metal. Paints can become porus. Use several coats and keep touching it up. POR works so well because it is a thick product. It is also very expensive and messy. I has gotten a small amount from them. I was not terribly impressed with it for the money spent. As with any paint "Prep is everything". For some of your stuff (like the jack pads) would a brush on truck bed liner be better (once you get rid of the surface rust of course)? I'm not sure a "one product fits all" would apply in your case.