Let me see if I understand....
YOu live in CT now, you are going to get the motor home and almost immed move to MT...
Why not just register at the new address? Then you can finish up the transfer of citizenship when you get there?
Why spend the money to set up an LLC?
NOTE: the LLC tax dodge can come back to bite you .. But if you are moving there, WITHIN THE NEXT SIX MONTHS (you said a few),
Why not just register there in advance of the move? At the residence you are moving to.. Work it out with the current occupants there as to mail and such.