I was finally able to spend more than a couple hours working on the trailer!
I started by welding all the vertical supports for the side skins, then all the flat steel for the edge of the flooring. The shop welder was broken so I was stuck using my little Lincoln 110 with flux core wire, after 20ft of bead I really wanted to vomit. That stuff is NASTY, but it did it's job and the welder is my trusty little stand by, so I can't complain too much.
I didn't bother taking any pictures in the process, but I'll get back to that in a minute...