Register RV in another state

Here's a rerun story I've told on here before but it's been awhile so I'll repeat it. A few years back I was camping with a group of people in a campground here in California. We were all in law enforcement and one was the County Sheriff. While we were sitting around one day the Sheriff started up with a guy in a neighboring RV who had a huge Montana 5th Wheel and a big one ton truck both with Montana plates. The Sheriff actually started talking to him because he wanted to move to Montana when he retired. During the conversation the guy revealed he didn't live in Montana, he lived in California and had never even been to Montana. He then went on to describe his Montana LLC and all the taxes he avoided and the fact that he keeps the trailer stored in California and makes sure it's behind his fence so nobody sees the Montana plates. During the conversation he asked us what we did. The Sheriff told him he was the County Sheriff and the guy looked at me and asked what I did. I told him I was a Criminal Investigator with the State Franchise Tax Board. You should have seen the look on his face, it was priceless. Then I let him off the hook and told him I wasn't. But I do think he learned his lesson about describing his tax evasion scheme to strangers in a campground.