A friend of our is a long haul driver and suggested we purchase a Deluxe Motor Carriers' Road Atlas by Rand McNally as a planning tool. It color codes every road in the US/Canada which is "trucker friendly". My thinking is if a tractor trailer can travel on these roads then I'm not worried about clearance hts of bridges, weight or propane. For small roads we use the list of bridge clearances provided by each state.
Just a thought....
Happy Trails