docj raises some good points and is on the right track. We currently live in AZ and going fulltime in January, we will be domiciling in, as docj mentioned, a state friendly to creating a domicile. In our case we are choosing SD, but there are others as well. The key with AZ and I believe most other states is weather you spend 30 or more days in the state and what really complicates proving you are not a resident, is if you are working in the state, perhaps own a house or have a rental agreement in force. These are the kind of criteria states may look at if they question your domicile status. Many fulltimers go the route of establishing a domicile in one of the states friendly to fulltimers without issues. It may be true AZ does not allow a UPS box or such as an address, I am not sure, but no matter, because in establishing a domicile in one of the states you will also need to get a mail service which will provide a "fixed" and legal address which should satisfy a legal address status.