Previous posters have covered it well. Something I always do is use Google Maps and Google Earth to preview things like fuel stops, entry and exit points from Highways, RV parks, etc. 10 minutes planning the night before saves a lot of surprises the next day.
The satellite views give incredible detail. If you are concerned about a particular road you can have a look at lane widths, shoulders, intersections - whatever you need.
2014 Newmar Ventana 4037 / 4018
2015 Jeep Grand Cherokee Ltd.
1940 Chevrolet Pickup