Where are you actually going to live?
If you are constantly on the road moving around, it can be a good option.
One item to watch is are you still officially assigned to Michigan in terms of work? It could be a red flag if you are working in Michigan but "residing" in South Dakota. The tax man has a tendency to assume you are guilty until you prove otherwise...so if you are really living 6 months of the year in a Michigan park, don't be surprised if they catch you at it.
Also, don't be surprised if they question the Montana LLC if there is no indication of actually having any relationship with Montana beyond using it as a tax dodge.