So many big items I thought to add serial or reg numbers to, exposed or hidden, with a bead of weld. I wonder how many states or underwriters care to insure trailers. Read any policy that you think covers your stuff, there can be a lot or not in the fine print.
Example: I had Allstate until the early '90s and they covered two deer collisions. (Since then they have become among the worst at paying claims, weaseling out, bouncing checks, stalling, etc.) Two yrs ago neighbor hit a deer and was worried about insurance. Full coverage? No prob, right? Called Farm Bureau and was told full coverage never includes car/deer collisions. Full of something, I say. A policy is only as good as the company that backs it.