How have your trailers held up camping in the mountains?

We camp almost exclusively in the kind of conditions you describe.

Other than "Sierra pinstripes", my trailer hasn't sustained any damage from mountain/rough roads camping. If you can call that damage...some folks, myself included, think of them more as badges of honor. Positive proof that we've been down roads literally narrower than the trailer...now, THAT is what I call "campin'! :B

Mice, by the way, are just as if not more plentiful in developed campgrounds, in my experience.