I use
Rand McNally Motor Carriers' Road Atlas
Rand McNally Road Atlas Midsize (It gets torn apart and stuffed into sheet protectors so I can write my route and notes on the sheet protectors with wet erase markers)
The Next Exit Interstate Highway GuideI replace every 3 years (not all at the same time). I prefer to run US Highways rather than Interstate Highways. Since US highways cross over Interstates, the Next Exit lets me know what is at those exits. The trucker's atlas let's me know what roads are not good for longish campers. Also easier to see the "truck bypass" for various small towns.
I have noticed that there is a lot of truck traffic on the US highways. It seems that the truckers are going back to the old US Hwy routes. I know I can make better time bypassing Atlanta's Interstates and taking US441. Adds miles but saves me hours. Plus it's not as stressful.
I use the CoPilot app on a cheapie Android tablet (it can go into my different vehicles).
I plot my routes online. I use my own personalized travel maps built in Google My Maps as well as Google Maps. I double check with my trucker's atlas. I outline the route in my sheet protected map. I check the Next Exit for potential stops. I load it into my CoPilot app.
#1 Get out and use a tape measure to see how tall you REALLY are. That not only means the distance from the ground to the top of the roof but also any thingy that sticks up above the roof (including antennas).
If you are in a fiver, hook it up and measure the highest point.
Write the highest measurement down and stick it someplace that you can easily see it without searching for it. You might want to include your loaded weight in pounds and tons as many bridges on secondary roads are rated in tons.