Back to the OP......
He stated he's going full-time and domiciling in Florida. He didn't say he was buying a house in Florida. Domicile is what full-time RVers do. They need to choose a state to domicile if they own no other home.
Montana LLCs are absolutely legal in this sense. That RV is not staying in Florida as far as I know. Thousands of full-timers have LLCs and they have no legal problems doing so.
Problems occur when you have homes in different states and live in a state and become a resident (which is altogether different from domicile).
When you hear of people getting 'caught', it's not because they're full-timers. It's because they actually live in another state. It's always best to set up a full-timer's LLC through a lawyer. Then you'll know the correct answer.
