You don't have to "live" in a state to register, tag and insure, a vehicle but you do have to have an address. For a number of years I was claiming Colorado as a home state to vote, etc. as I owned a home there. I also had vehicles tagged and registered in Oklahoma as we owned a ranch there but didn't live on the property except for short visits, also still owned a home in Alaska and one in Florida. We were rapidly going broke, house poor so to speak. But I had vehicles in all the places but that is where they stayed. On a rare occasion I might drive one of my ranch pickups from Oklahoma to Colorado for a specific reason, but the truck went back to Oklahoma as soon as possible.
Our RV was tagged in Colorado, as was my driver's license. I had to pay $7,400 in sales tax to Colorado, when we moved there as I had purchased the Moho in a non sales tax state, Alaska. Now Colorado would have gotten very aggressive quickly if I had tried to domicile my Oklahoma tagged vehicles in Colorado, without tagging them in Colorado. You have to, in most cases, tag your vehicles where you plan to use them, on a permanent basis.
In Oklahoma, I gave the tag agency both a physical address, our ranch, and a mailing address, our Colorado address. We also ran a private mail box in Colorado for other reasons. I did the same in all the states. They want a physical address to find you if necessary, just like the address on your driver's license.
Many full time RVers establish a relationship with the Escapees Club in Texas. It is actually a privately owned business but has campgrounds, will receive mail, etc for you, you can use their address for everything including filing you federal taxes, etc., get a Texas tag, driver's license, etc and do it all in a lawful manner. Texas doesn't care how much or how little time you are in the state. Any state that feels someone is trying to evade paying state taxes owed, is going to have problems.
Florida, for one, is a non income tax state, so everyone, including our great Canadian snow birds, pay the state sales tax. The state appears to be more concerned with collecting state sales tax than the small amount collected on vehicle tag revenues. Sometimes it seems that half the car tags I see are from other states or provinces. Now for some unknown reason Florida does seem to get excited about out of state boat registrations, go figure.