It's occurred to me that I found a good way to test a trailer's weak points when I built it up. What I did is I showed it off to the teens at the park near my place, and let them play with it and generally give it a good beating, until something broke. Then I fixed/beefed it up and let them have at it again, and the process got repeated. But after that nothing more broke on it. I figure this is better then having it break down when far away and actually hauling stuff.