Can we just expel them from the US? Keeping control over some naval bases, of course. They'd be happier and the rest of us would be, too.
Or maybe we can encourage the California secession movement, and when they win a plebsecite, Congress can pass legislation implementing terms of secession: the naval bases, plebescites in border counties to allow them to leave California and join neighboring states, and a free trade agreement (too many supply chains have links in CA to put of a hard border even if they're gone).