That's been the brunt of this discussion. The OP states that the dealer told him he could do it with his ID address. According to the MVD, you can TITLE the RV with a non-NM address, but you have to be a resident (and show proof) in order to REGISTER the vehicle.
The OP has argued that it can be done but has provided nothing to back that claim up except for saying the dealer told him they could register it for him with the ID address.
All this is moot for the OP (but I think it's important for folks coming across this post in the future) because he has decided that he will register the RV in Idaho.