No concealed carry except in your residence (which includes your hotel room, your campsite, your RV when used for that purpose, etc.) or on private property not open to the public on which you have a right/permission to be and where those responsible have no problem with you carrying. Also allowed while hunting and fishing (with some caveats). Pretty limited. Everything else requires a California permit, and you don't qualify for a non-resident permit (pretty much just for people who work or have a business in CA, but live outside of it, and has limitations compared to resident permits; not for tourists).
Open carry without a permit is only allowed in unincorporated areas where discharge is not prohibited. Doesn't sound like you'll be going to such places. Official roads count as places where discharge is not permitted, so vehicle open carry is pretty much just while offroad or on unofficial dirt roads in the former sorts of places. An exception is for percussion, flintlock, and similar firearms with separate ammunition, but it can't be primed alternatively, it can be primed, but not loaded). Obviously if you're legally hunting with a handgun, you can openly use it.
In a vehicle, you can have your handgun unloaded on a locked container. Mags can be loaded and you can possess ammo, and that stuff doesn't have to be locked up, just the gun itself. Ammo in a sidesaddle or something like that does not count as loaded, but you can't have any in a chamber, cylinder, magazine that's in the magazine well, a fixed magazine, etc.
Transport outside of the vehicle is the same as above, but you have destination requirements. You have to be going immediately to and from authorized places, like your residence or other private property where you have a right to be and can possess a gun without limitations, a FFL or gunsmith, a gun range or area where shooting is allowed, the place where you're hunting or fishing, and I think a couple of other places. Anything more requires a permit.
For long guns, if it is unloaded and in a locked container, or in a container designed to carry a firearm (doesn't have to be locked or lockable; I think that a gun sock technically counts), you can have it in your vehicle or on your person, openly or otherwise concealed. Can be openly carried for hunting, but not fishing, otherwise the same conditions under which you have no carry restrictions apply as for handguns above. If you're somewhere you can legally open carry, you can also conceal the long gun, instead. No destination requirements/restrictions.
Obviously, be aware of our AWB. A pistol with a threaded barrel is an AW. Also, the only NFA stuff allowed to be brought in are AOWs, C&R SBRs and SBSs (by age, at least 50 years old), and DDs under .60-cal., assuming you have a stamp for them. Respecting AOWs or other handguns, braces are not considered stocks here, but most rifle-receivered handguns would be considered AWs here. Also, no magazines with a capacity over ten rounds, other than fixed tube mags on .22s, can be brought in, nor possessed if you are not covered by the injunction (which you would not be). If your long gun has a dedicated rifle grenade spigot, it will probably be treated like a DD possessed without a permit. If you want to know if what you want to bring is an AW, just ask.
No ammo restrictions other than tracers and incendiary ammo.
We do have a State gun-free school zones law, so you have to have everything locked up and unloaded when in public within 1000 feet of a school, including long guns, since you don't have a CA permit. In denser areas, you'll be in such a zone a large percentage of the time.
Be aware that CA has a 4th Amendment "exception" in its laws. If an officer has RAS or actual knowledge of a firearm on your person or in your vehicle and you don't have a carry permit, he can search for firearms and inspect them to ensure they are being transported according to the law without probable cause or a warrant. Best not to let officers know about your firearms or give any indications that you have any (like gun cases or ammo visible). CA does not have duty to inform, which is helpful in this context. In urban areas you especially want to avoid dealing with the police when it comes to guns. I'm not even sure a non-resident can get a gun taken into police custody (even wrongfully or for non-criminal reasons) back from the police due to the nature of our gun release rules, which are onerous even for a resident, absent a successful lawsuit.
More thorough than you probably need, but I figured I'd cover all of the bases. There some other things, but they don't apply to non-residents, especially visitors.