Perhaps others have already seen this, but I just found http://truckrouter.com/, which is in beta. It is online software, you have to say you are a truck trailer, but then enter your weight, length, height. Enter your start, any way-points, and your destination.
This was of value to me as I planned on Cloudcroft, NM. Hwy 82 out of Cloudcroft towards Alamogordo, NM descends over 5000' in just 16 miles and includes a tunnel. Whoopee! So this software provided an alternative route that is truck friendly. My prior GPS from Rand McNally was supposed to help with this, but I found it to be untrustworthy.
Suitable for motorhomes with toads and fithwheelers.