We use a Garmin RV-specific GPS (the Garmin Dezl truckers' GPSs work well, too). With these, you enter the parameters for the rig (total length, GVWR, height, width, etc.) and they will route you around any place you shouldn't be. There's also a publication called the Motor Carriers' Road Atlas for truckers that's basically the same information in hard copy. As stated above, stick to the Interstates and US highways and you'll be fine. If you don't see 18-wheelers coming and going on a road, start to worry.
Rob
U.S. Army retired
2020 Solitude 310GK-R
MORryde IS, disc brakes, solar, DP windows
(Previously in a Reflection 337RLS)
2012 F350 CC DRW Lariat 6.7
Full-time since 8/2015