Just to follow-up on this for other people's benefit. The white crud was a pain in the arse to get off. It took a lot of aircraft stripper, tools to scrape the junk off, high-speed sanders with varying grits and a lot of hard work by not only me but other folks to get it the metal back to a position so it could be polished. I would highly recommend that no-one puts more of that nasty kool-seal or comparable products in places they don't want it to come off later. Keep that junk at the very top of the trailer and avoid going down the sides vertically.
Furthermore, I also tried a small section with a soda blaster and wouldn't recommend that either to get it off. It did more damage than good.