I don't know (maybe you said but I missed it) if this was an enclosed trailer or one of those car dollies that you put the front tired on. But now that you are flat towing, one of the interesting things that happens, to me anyway, is the smell of burning rubber that seems to accompany your toad the first time you drive it after a long haul. I thought something was seriously wrong and searched everywhere for the problem. Finally mentioned it to a friend who said that was normal after towing for awhile.
Just thought I'd mention it.