We could opine all day on the morals and ethics of such a thing, but morals are usually difficult to enforce legally. But LLC's to avoid paying taxes is under pretty heavy scrutiny, and if you pay attention to the media, it's about to get a lot more attention.
But a few things I would ponder. This topic comes up periodically and I recall about a year ago there was some evidence that states were cracking down on Montana LLC's, even to the point of monitoring forums like this one.
Can you or an attorney can provide defensible answers to questions like; "is there a legitimate business need for your RV under your LLC?", "What is your business and it's purpose?", "Can you evidence why you live in one state and have a need for an LLC in another state and further - that need includes RV ownership?", " For what purpose do you need to have limited liability and how does an RV in another state perform in that liability limitation?", " Why did you open an LLC in Montana when your residence is TX?"
I think most times these LLC's fly under the radar. But if you get audited, be prepared to answer questions like the ones above. And if you can't defend it I am sure there are fines as well as back taxes due.
Lastly I would caution asking the question here. Unless some forum members are attorneys familiar with setting up a MT LLC your answers will be all over the map and hardly legally valid. And asking the question, especially the way you asked it, could draw the wrong attention. After all, you stated your purpose very clearly.