Why avoid California? It's easily one of the most beautiful states, has a tremendous coast on the best ocean, the incredible Sierra Nevada mountains and much more.
You wrote you wouldn't consider traveling without a firearm. If you're concerned about crime, there's no reason to be fearful of California. Lots of little old ladies get along there just fine. Having firearms in California isn't an impossible ordeal either. Don't try to bring a so-called assault-weapon styled gun. Don't carry any firearms concealed. Don't transport firearms loaded. Transport them in a "secure" container other than the glovebox or center console. A locked bag, box, or case suffices. Once you are "camped," you can have a loaded firearm in your camper or on your person.
This isn't intended as legal advice and I don't think you would expect to receive that from a stranger on the internet, but if you look up the laws yourself you will find that you can use firearms in California to protect yourself and your family from threats of deadly force.
Is California a free state? No. It's laws are onerous, but they're not worse than Hawaii. I simply would not allow myself to be so cowed by criminals that I would not visit California or Hawaii just because I couldn't carry a loaded gun everywhere I went.
I didn't get the sense that you were intimidated by the law in California or any other state. You're probably aware that if you're a lawful person, there's no reason to be scared of lawmen.
Personally, I would be sure to visit San Francisco. It's an absolutely wonderful city, easily one of the best in the world. It's very sad that it's been ruined as much as it has been by the prevailing politic and immorality and corrupt culture that permeates it nowadays, but none of that is a reason not to enjoy all the good it has to offer or to avoid the opportunity to marvel in its history. I love to visit it every year and other than Manhattan and London, it's really the only urban area that I can enjoy being in at all (though I haven't traveled much outside North America and Europe). I can't recommend driving the RV or truck into the city, though it's not impossible. One of the best times I had there, I rode in from across the Golden Gate bridge on a bicycle tour. San Francisco is one of the most walkable cities because it's geographically constrained to short distances, but a bicycle is an ideal way to get around it. Otherwise, it has good public transit like the street cars and of course the cable cars. You can meet a lot of neat people too. It's true a lot of them are in sad condition, but that doesn't make me feel contempt for them, but pity. Mostly, you meet other tourists. If you do take a vehicle, consider parking the RV for a couple days and renting a car. It will make parking easier, but not cheap. Riding BART into the city would free you from the vehicle.
I already mentioned all the coast that would be missed without visiting California. I'd especially highlight Point Reyes National Seashore and the Point Lobos (Monterey and Carmel) area and Big Sur. These are great places to RV.
Yosemite National Park is a treasure that you'd miss if you skipped California. It's also a good place to take an RV or camper.
Lake Tahoe is the best large lake in America. You can visit the Nevada side without missing out on the lake itself. The California side has Emerald Bay which is worth visiting. It's all a tourist area. There are pristine wilderness lakes in the high Sierra Nevada, but Tahoe is a major resort area. It's not the place to go if you hate Americans, but it's a great place to take an RV.
I don't live in California, but I know how much I'd be missing if I didn't ever visit or bring my kids there. If there is anything wrong with California or what's happening there, knowing what's being lost makes it all the sadder. I'm not going to abandon a great state of the union just because of how some people there think or vote or allow lawlessness to abound. Seems to me Americans should stand their ground.