Where in CA?
If you have guns outside CA, don't bring them in. You'll have to register otherwise.
Illegal guns will be a huge liability. If you actually defend yourself with them, the court will completely fuck you. Practicing will be an issue (you should only practice with rented guns anyway, if you can even find a range in this hellhole). Generally there are a lot of technicalities that will be used against you. Don't fall into the trap of thinking just because you can rationalize this one loophole in the law, you're safe.
Something like a crossbow, black powder revolver or C&R is probably a better solution. At least its technically legal.
Your threat model is a bit fanciful even if you lived in Alaska. Just 1v2 is shit odds, 1v4 is practically hopeless just due to numbers. And you've stacked the deck in their favor: They have armor, presumably more experience and better guns (since they have armor), got the drop on you, you're half asleep. And what do you have? Guess you know the location better.
If squads of armored men start kicking down doors at 3am one day, the most productive thing for you to do is ensure that you will not stick around for that day. Whatever is keeping you here for 2-3 years, work on making it go away sooner. It's guaranteed to be an easier problem than getting funs in CA. If you suspect that you specifically will be targeted, same thing - gtfo asap, and maybe don't do things that will make you targeted.
DL is not required, just government photo ID. You could use a passport or something. But apparently CA specifically prevents you from buying even in other states.