Having lived in AZ for 31 years this is my understanding. As long as vehicle registration and driver's license are from the same state there will be no issue. We had many people move here and be required to get an AZ driver's license to work. They would leave the car registered in the home state if their registration fees and insurance were cheaper. It was easy for LE to distinguish these people during a traffic stop. I know many tickets were issued.
In your situation I assume that the vehicle and your DL are both WA state so how does anyone know how long you have been here? While LE may ask,and that is highly unlikely, you are under no obligation to answer, just don't lie. The bigger issue is the coming heat. At some point in the near future it will be way too hot for RV life in AZ. You may have to move to a higher elevation or head home to avoid this.
RichH
