As someone who has been there and done that, and gotten caught, and had to pay the state of Illinois nearly $7000 in sales taxes, just don't do it.
In my case, I did not establish a domicile in Montana. (most don't, right?)
And many if not most states require vehicle registration to be transfered if the vehicle is physically in the state for 31 days.
And they are on to the Montana LLC thing. When I bought the Knight in Florida, titled and registered to my Montana LLC, Florida sent a letter to my state of domicile (Illinios) the same day they issued my temporary tag.
The revenuers are talking to each other. They are trolling these forums.
I would highly discourage anyone from trying to title and tag any vehicle in a state they do not "live" in. As in vote in, own property in, pay taxes in...
Signed,
"Been there, done that, got the tee shirt."