Rand McNally has a PND for truckers. It will do hazmat routes, doubles, etc. I'm not sure about weight limits. Check
Rand McNally TND500 - Great Eagle Tech
I have an RV and much of the travel information is in truck form instead of RV and I've never seen anything with weight limits. Obviously, interstates would not be a problem. The number of bridges in this country would probably make it impossible to try to categorize them.
The Discover RV web site has overlays for
Streets & Trips,
Street Atlas, and others, that can be useful. They'll show you many height limits, Pilot stations, Flying J stations, Wal-Marts, Sams and much more. It's at
http://www.discoveryowners.com/cginfolinks.htm