Wow, Joe, that is an amazing and terrific story -- well done! I guess there is an element of luck here -- I got lucky (as described above), although not as lucky as you were. Others have not. Part of the luck (skill, actually) would be in inspecting the used trailer very carefully before buying, something I did not really know how to do when I bought my first one. (More luck -- as it turns out, there was nothing wrong with it.)
Knowing what I know now, I would have hired someone knowledgeable to inspect it for me.