Interesting.
So, when our mailing address was a PMB at a UPS store in Montana, and we had no owned real estate nor a rented house in Montana, and we spent 13 weeks in Washington, then 13 weeks in California, and 13 weeks in Montana then began the rotation over again, and the trailer we lived in was registered in CA, but the truck was registered in Montana and our driver licenses were Montana, and we paid Montana income taxes as well as CA income and sales taxes, and WA sales taxes, and the address on our checks was the UPS store address, where was our "domicile"? Obviously, we could not return to Montana and take up residence in a UPS store!
It would seem that the rules and regulations are often divorced from reality.
Which is not at all surprising!