I have just the thing for you,...
If you dont mind setting a laptop on the dash the "copilot truck" series of gps software is the best.
It is based on "pc miler" truck routing software.
It has all the nifty features my car gps has, garmin nuvi 770.
This copilot software all but grabs you by the throat if you try to anything remotely stupid.
They have an RV version but I wanted the hardcore truck version.
When I set it up I chose to make it think I am a rig pulling a 53 ft trailer.
Never even came close to putting me anywhere that the bus wont fit.
Try it you'll like it.
Cheap money at $299.00