Sticks, I am not a lawyer and I don't play one on TV, but if I were one I would ask you a few questions because you are clearly entering an area where you need to do some risk versus reward calculations.
To anyone with an IQ above room temperature a Montanna LLC is a tax EVASION technique. Unless you specifically have a business purpose for the Montanna LLC, and that business requires the use of a coach your only purpose is to not pay sales taxes that your home state would impose.
Some states have already started going after the taxes they feel entitled to collect from folks that have put their coaches in a Montanna LLC. So here are some questions. How long do you keep your coaches? Obviously if you flip them routinely, an LLC will save you a lot of money in sales taxes. How risk averse are you? Your home state may never go after tax evaders. Are you willing to risk that? All it takes is a grumpy neighbor to turn you in and make your life miserable.
Are you willing to do all that is necessary to insulate yourself from grief? To really appear to be based in Montanna and have a purpose can you find a way to use a coach for business purposes? Are you willing to register the toad there? What about getting a driver license there? There are still no laws against anyone having two domiciles.
I spoke to a guy many years ago that tried to beat California out of its sales tax by registering a new Prevost in Nevada. The trouble is he continued to tow a California registered toad and still had a California driver license. He was caught, and his costs were the sales tax, interest, and a $75,000 fine. As the states get caught up in our debt crisis they are going to go after every penny they can. Big fancy buses are very visible targets and the average voter and citizen is likely to love seeing the rich folks get spanked.