Don't know about CA, but this may still help you. I live in NC and I have my CCW permit. It does not include long arms or martial arts weapons. What I have done is bought a rack which is mounted to the roof of my truck against the headliner. It's called the Skybar, holds two guns or one, and I got it from Cabela's. I believe it was about 60.00 for the one gun and 70.00 for the two gun.
Hope this helps your dilemma.
Carry it open, such as a rack, unloaded with the ammo in another container. Carry it concealed in a case with the ammo in another container. Get the gun and ammo as far apart as is possible. Keeping the ammo in a lockable container is also a very good idea.
12021 PC specifically disallows a loaded firearm in public and also gives a peace officer the right to inspect the weapon to make sure it is not loaded.
In CA, longarms are not considered "concealable" firearms. You can legally carry a shotgun behind the seat of your truck as well as in a rack in plain view. It does not have to be in a locked container. However, in CA, a firearm is deemed loaded if ammunition is attached in any way to the firearm. Make sure there are no rounds in the magazine (assuming the shotgun is a pump or auto with fixed tubular magazine). If you happen to have a shotgun with a detachable magazine, you may have the magazine loaded but not attached to the shotgun. The safest method is to make sure the ammo is in a completely different place than the gun.
Greg, most of the time, unlimbering the unloaded 12-gauge would do the trick, I'm sure. That one time in 20 when it didn't scare off the goblin would be really embarrassing, though. Yelling "Bang! Bang!" isn't all that effective.
If God didn't want us to own guns, why did He make the 1911?