Two years ago, I met a guy in L.A. (lower Alabama) in our winter park in a gorgeous Prevost a couple of years old. Turns out he was a major car dealer from middle Illinois and had researched the Montana LLC thing with a Montana lawyer, had his Illinois tax attorney go over it closely, got a thumbs up and pulled the trigger.
A year later, someone ratted him out after seeing his Prevost in his driveway in Illinois. Next thing he knew, he was being threatened with tax evasion and jail time. He was to be the poster child for playing fast and loose with the law. Over $100,000 in fines and back taxes later, he was pretty sure the Montana concept had some serious limitations in his case.
Another guy in the park, also from Illinois, had his insurance canceled when they found his coach was registered in Montana while his other vehicles had Illinois tags.
You can argue the pros and cons, and you can take the two items above with a grain of salt. It's also obvious this is an RV Forum, not the law review. You can decide based on your circumstances. It's not for the rest of us to judge.