I find enough of a challenge remembering all of my travel destinations on a timetable, and with full respect for laws and safety, so would not want to have to pay attention to whether I am carrying any kind of high-profile load.

I remember once entering a public parking garage and forgetting the high-top fiberglass shell I had just installed. I actually backed up and checked the actual clearance and it was 2", too close for comfort. But I've never hit anything with the shell in 26 years, if only because it's not all that tall.