Mik68 -
It would appear you have done your necessary homework..:C
Discuss with your mates where your immediate travel destinations will be. What you want to see and do - and the travel distances from L.A. or Dallas.
Bottom line of costs between the two - is pretty much a wash.
If purchased in California you can (legally) avoid sales tax if you take delivery out of CA.
CA *residents* have been doing that for years - via the "CA 90 day rule" - which is now one year.
Standing joke about some Nevada campgrounds - they looked like ghost towns due to all the empty RVs.
Unfortunately, you must register 'somewhere'.
I would be looking at those options -vs fees- as part of your research.
You can register (both) in South Dakota, without physically going there. SD has 3% sales (excise) tax, and *dramatically* lower license fee/s than CA (especially for the trucks).
Contact any one of the mail forwarding services in SD such as "Americas Mailbox" for more information.
Hope you enjoy the visit - wish I was planning the opposite adventure!..:W
~