....as long as you only travel on the interstate!
Overhead obstructions on secondary roads can be much lower. There was a steel bridge that I used to cross that had an 11 foot clearance. Also, if you plan to do any backcountry driving on forest service roads, you have to worry about tree limbs.
I really want to have a deck on my bus someday, but increasing the height is a drawback to keeps me from building one.
...that and the fact that I don't have the money, time, or tools to do it....