TXiceman - I agree that can be helpful to have. But planning routes also can help a lot. I try to stick to US or state routes as they have some requirements for notification of lower then 14'6" clearances, most county roads too. I also have no problem calling local campgrounds to check if there are any known low clearance areas to worry about since the 5th wheel is nearly 7" taller then my old bus was.
I have not had too many issues getting to campsites this way, but have been considering a trucker/RV gps in the future. So far the only issue I had was parking in my normal storage area. The tree was trimmed for the bus to get under it, but the 5er being taller actually snagged a branch and bent the antenna. Thankfully that has been my only clearance issue to date.