Well, if he really wants to Trump-proof California, perhaps they should secede.
And we should let them go, with some conditions: (1) All counties adjacent to other states get to have plebiscites on whether to leave California, and join the neighboring state, (2) We get a lease in perpetuity on all Navy and Marine facilities remaining in California, (3) the California dollar (or peso) is pegged at parity with the US dollar for five years, then allowed to float, (4) they assume a share of the Federal national debt, half in proportion to GDP, half in proportion to population, (5) newly seceded California pays for people wishing to leave to move to a location in the remaining United States as part of a voluntary exchange of populations -- all people choosing to remain in seceded California cease to be US citizens and become citizens of the new Republic of California, as do all US citizens who choose to move there with the intent of remaining during the first five years after secession.
Either that or we should oppose it, invade an impose radical reconstruction measures.