Ah, yeah that is a tricky situation. If you have a car I would recommend keeping some things inside that would be helpful like a life straw or similar water purifying device, small medical kit, matches, flashlight, extra batteries, some dried/dehydrated snacks (jerky, fruit, veggies, etc.).

Extra cash on hand and one or more bitcoin/lightning wallet options. Maybe a little safe somewhere in the car for some extra security.

Obviously having a lot of this in your car comes with higher risk of theft but you work with what you have.

I'm a big proponent of conceal and carry. Not sure how easy that is in California but also worth considering. If not a firearm, some form of self defense (knife, pepper spray, tactical pen, etc).

Might also be worth having a physical map in your car and to plan out your route some months in advance. Consider who you trust and areas you know and stick to that route and those places/communities. Might be worth keeping a distance from major urban areas too.

Hope this helps!