Full Faith Clause of the Constitution
Article IV, Section 1:
Full faith and credit shall be given in each state to the public acts, records, and judicial proceedings of every other state. And the Congress may by general laws prescribe the manner in which such acts, records, and proceedings shall be proved, and the effect thereof.
What does this mean to drivers and vehicle licenses?
The Full Faith Clause means that every state has to accept a drivers license or vehicle registration issued by any other state.
In more direct terms, if your registration state says you have a HDT registered as an RV and that vehicle can be driven by a Class C license, then every other state has to accept that combination of vehicle registration and drivers license.
Some caveats, it is really smart to have your drivers license and vehicle registration from the same state to preclude question on the combination for and Law Enforcement Officer.
What about Commercial?
By definition Commercial vehicles are uniformly registered in all states. The standards for a Commercial registration are established by the Federal Government since the late 1990's to facilitate Interstate trucking.
Commercial licenses (CDL) are like the Commercial registrations. The rules are exactly the same in all 50 states and the District of Columbia. When you get a CDL, all the other states are notified that you have a CDL. This prevents a driver from having more than one license as was a common practice before the late 1990's.
Why is the Full Faith Clause a Consideration?
The states have no options with the Commercial licenses and registration. But they have a lot of flexibility with non-Commercial. That is why a HDT can be registered in one state as an RV and not in another. The license to drive a 26,000+ vehicle can be done with a Class C as an RV in one state and with a CDL Exempt license in another..
Without the Full Faith Clause, you could have to register in each state you travel through and get a drivers license. The Full Faith Clause was created in the Constitution to allow numerous activities to happen between the states, not just vehicle registrations and driver licenses , but it is a good example why it was needed.
However you can register you HDT in you residence state, you can drive it through the United State.