Welcome to the forum. As a new TT owner myself, living in an area of the country with tunnels, this was a big concern for us as well. We live in the DC area and I am from Massachusetts, so we travel alot up and down the 95 corridor between DC and MA. Anyways, after lots of research, we settled on a Garmin Dezl Trucker GPS. It has an RV mode, but we just use it in truck mode. So far it has successfully kept us from low over passes or from propane restricted areas. You have to order online, they dont carry it at the store, but it is free shipping if you get it shipped to the store. We have only used it a few times for trips down to the Greensboro NC area, and to Virginia, but it hasnt given us any problems at all.
Garmin dezl 760LMT 7" GPS with BuiltIn Bluetooth 010-01062-02 - Best Buy
You can also have different profiles in there if you had multiple trailers to tow, and there is also a "car" mode, so when you are at the camp ground and want to find a grocery store or something, you dont have to take the truck route (which can sometimes be significantly longer). Just enter in a profile name for your trailer, input the height, width, etc and it is suuposed to keep you out of trouble. From the research we did, the common theme was that RV mode can help you find RV specific stops, but it actually doesnt avoid propane restrictions, but the truck mode does. That makes no sense to me, but who am I to tell Garmin what to do, lol.
It will also clearly show you what lane to be in at exits and turns (like when there are 2 exit lanes, sometimes it is important to be in the "right right" lane, and sometimes it is important to be in the "left right lane", lol). There are many options out there, we decided this was right for us (didnt hurt that we have been long time garmin users and was familiar with how garmin typically works). Hope this helps a little, we spent several weeks doing our research. I am always willing to help, just hope I dont steer you down a path that doesnt work out for you