DO NOT put total trust in GPS and that trucker feature won't help. If you trust that your asking for trouble. I could post some examples of people who blindly followed GPS instruction. Here is just one example of someone trusting that feature you described. Blindly following GPS equals trouble
I can post some more.
1st you have to understand GPS and the HYPE! There are only two companies that provide GPS mapping used by "ALL" GPS units. What that means is they are all flawed! I won't get into Garmin vs. Tom Tom debate but both are equal not one better than the other. Just features and both offer same so lets stop any branding of GPS, ALL are good. That said don't follow them blindly use them as designed, driving aid!
I've had my rig almost 4 years now and have yet to find over pass too small. Thats more the exception vs. the rule if you stick to major highways. Then you just do some research in advance on the roads off freeway you will travel.
When in doubt, approach slow so you can read, stop if necessary and turn her around. Its really not a problem, just use common sense and you'll be good to go.
What ever you do, DO NOT put your trust into electronics. Trust your gut and use some common sense and plan your trip. JMO nothing more..
Good luck and enjoy that rig!