Get a Rand McNally GPS. Enter the specs of your RV; width, height, # axels, size of propane tank, weight. .... it keeps you safe. RM keeps track of all state by state, road by road and routes you safely. With optional TRAFFIC-EVERYWHERE it advises you just like Google Maps. There's lots more, like where the tank dumps are. RV GPS
Did I mention that the PC interface enables trip planning on your computer and then download to the GPS unit? Or the fuel log with auto calculate? Oh, and it tells you where to find fuel and the prices at all stations. There's more. Chechnya it out.