We've been taking a yearly tax deduction on our rig and don't fulltime. In no way can a RV purchase be considered an investment since their return will never ever exceed their initial and continuing costs.
My DW and I travel on business often and we do prefer RVing for personal travel, although under some circumstances hotels must be used. We could do the math and give it a slant to make the outcome favorable but why bother.
Whether you live in it fulltime, do extended stays, or just a weekend RVer, it costs unrecoverable $$$ to enjoy the RV lifestyle. Sure you can digest it mentally as financially prudent, but we all know better.