That would be both easy and cheap.
The south 2/3 of the eastern State line is killer desert or the killer Sierras..
The remainder, north of Tahoe is totally defensible; all invaders will easily disappear, courtesy of those Counties with the original Pioneer "American" spirit.
That's perfectly acceptable...
Yes, it would be easy and cheap. My mom’s family is went to
the northern CA-Oregon area in the early 1800’s. They never put up with any nonsense and I don’t think they are doing so today. I wish we had a State of Jefferson. It is time.