I double tower a Smart4Two behind our 37 ft. 5er and Volvo VNL 610 for two years with no trouble.
Went from West Texas to east Tennessee,, down through Georgia, Alabama, Arkansas, Louisiana and then to New Mexico, Arizona, Utah and Coloardo with no trouble at all. I was just short of 80 feet. I even got caught in an HOV lane with heavy traffic in Nashville. I got some ONE FINGER SALUTES during this experience.
ShortyO