As a full timer, you are allowed to choose your 'residency' State. That said, there are many variables to consider. We had not purchased our new motorcoach yet, so sales tax was an important consideration for us. California's tax was 9 3/4% and South Dakota was 3%. On a $500,000 purchase that represents a sizable savings. Also SD has no income tax. Whatever State you choose, in order for the IRS and others to recognize your choice, you must establish your 'intent' to make that your residency State. That means you'll need to transfer bank accounts, voter registration, tags, driver's license and everything else to your chosen State. Property ownership is NOT required. We established our intent early by choosing Americas Mailbox in Box Elder and began transferring everything there before I retired. Once I retired, we had established ourselves there with the exception of our driver's licenses. After purchasing our coach, we traveled to SD to obtain that. We chose Box Elder because it's in Pennington County which has no 'wheel tax' saving us a bit more in taxes. SD also has no vehicle safety/smog inspections to worry about.
Two other considerations to think about are insurance, only a few companies insure full timers, (think car insurance and home owner's policies rolled into one) and it costs more, and health insurance, which varies from state to state.
Most of these decisions are based on your own particular situation. You'll need to do your own research on which state will provide you the best bang for your buck. Whichever State you choose though, you'll have to establish your 'intent' as stated above, to avoid any legal hassles...best of luck..Dennis