I was ready to unscrew one of the sides and move it forward about a half an inch even though I knew it made no sense, and it would a real pain in the arse when I remembered I was working in three dimensions. The trailer was racked (it wasn't flat). I broke out my floor jack and jacked up the back corner of the side I thought I had was going to have to move forward, and Viola!!!!! everthing started to square up.

I just wanted to let any other newbies know that Harbor Freight trailer might be square length x width, but it might not be flat.
I am working tomorrow ( Happy 4th of July), but I am hoping to pull my "Gnome Home" out of the garage to start sanding and get a few pictures to post on this site.
edited to say even thought there is a frame forum, I thought it belonged in the tips forum. If the moderators don't agree, please move it.