My rule of thumb for this type of issue is - can I defend my decision for any other reason other than to avoid paying taxes? What I mean by that is, are you doing this solely for the purpose of tax evasion? If so, then you have your answer.
If however, on the other hand, you decide to register the vehicle in another state because it will be located in that state the majority of the time, or you intend to retire to that state in just a few months and don't want the hassle of changing over the registration, or something like that then you have another reason beyond tax evasion.
Basically I am trying to play out in my head, in advance, what I would say if I were ever questioned about the situation. If I can not come up with anything that sounds reasonable while I have all the time in the world, then I certainly won't be able to when I am stopped by the side of the road talking to a police officer.