Residency is based on a physical address, where mail is delivered. Having utility bills helps, but really all you need is to be able to receive mail there for over 6 months out of the year. An RV park, an apartment, even an extended stay hotel room will do, so long as you can get mail delivered to it. That's how a lot of people get away with having just mail drops and establishing or maintaining their residency requirements from that. It usually works pretty good unless you are trying to avoid alimony or some such.