Admit it - we've all done clueless things! OK, here goes. I pulled a trailer for the first 12 months with the heavy duty tow bar upside down on my Ford Futura. I kept wondering why the trailer was so low at the front. Then one day I saw the same towbar on the back of a higher 4WD and this light went off inside my head - take off towball, turn it around 180 deg, put tow ball back on. Trailer rides level!
Duh!