The one thing to remember when car topping or trailering something like a mast, is that sometimes the payload will turn wider than the car......An 8+ racing shell, for example, will hang over the front and the back of the trailer, and the front will end taking more turning room than the car......snap. I was there when a Wendy's sign took out 2 quads. The slow motion crackling of carbon fiber caused nightmares for months.
With that said, when I was rowing, we used to make long hauls with a good bit hanging over each and and johnny law never bothered us.....We would car top the singles and they are roughly the same length as a small mast. ~25 feet.
and the back end of a trailer