If your question is about forming a limited liability company under false pretenses to enable yourself to pay lower taxes through a state that you probably will spend very little time in, then it is evasion. It doesn't matter if you are talking about sales taxes or ownership taxes. You can establish an LLC in California or Arizona just as easily as Montana.
Here is the same discussion on another forum - but you may already know that -
http://www.rv.net/forum/index.cfm/fu...g/1/page/1.cfm
You'll note that the State of Washington will not let you enter the state or use the roads if operating under a Montana LLC for no other purpose than to plate your rig. Oregon is close behind.