The Joe Arpaio tent city idea is spot on, and interestingly, it is legal by international standards. That is, some years ago, there was an effort to establish what “human rights” exist in dwellings. But the nations with large armies insisted that “military field conditions” do *not* represent any violation of human rights.
This means that the only thing possibly preventing the State of California from doing so are liberal federal and State judges, who think it is up to them to decide what prison health and welfare standards should be.
But if the SCOTUS makes a clear ruling on the subject, then California should immediately construct a dozen or more very large, rural tent cities for inmates. They are far cheaper than brick prisons, can be put up in just a week or two, and can be put far out in the desert, only constrained by availability of water, power, and food.