Good luck in California. The sheriff denied our ccw applications and we are very experienced with firearms. Besides move to a different county or out of state what does one do? I’d also recommend this org for self defense insurance.
Regarding self defense, a firearm in my opinion is the "nuclear" option. Absolutely the last resort. There are many practices to use to avoid a problem. You might try "Refuse to be a Victim" course. There are many practices that are common sense and others that are very practical. Then you can use many levels of products to dissuade an intruder.
If you must and are current with a firearm, I believe you can have one in your RV as long as you follow the law "Pursuant to
California Penal Code section 25610, a United States citizen over 18 years of age who is not prohibited from
firearm possession, and who resides or is temporarily in
California, may transport by motor vehicle any
handgun provided it is unloaded and locked in the vehicle's trunk or in a locked container. "
Quick access containers are easily available.
If you choose the firearm route, please attend a "Run and Gun" at
night training. When the lights go out and you have to move while under pressure, things are very different. Our local club puts on a IDPA/IPSC type course for a night shoot. It allows you to become accustomed to the flash and bang in low/no light situations. Bad things usually happen in the dark.
Speaking of dark, we are planning to install LED lights on both sides of the RV. Not only useful for Docking lights but when things "go bump" in the night. If you want to get fancy you can install RGB LEDs and have them flash Red and Blue

Remember a bad guy is typically looking for an easy mark, don't be easy.
And let me add a personal belief, never announce your intention or response to an intruder. Some folks claim "racking a 12 ga is best protection". I disagree, in today's world an armed intruder will shoot first, rob your corpse and claim "self defense" if caught. In California your estate will probably get stuck with a lawsuit from the purps lawyer. :-(
One last thing, have insurance specifically for this purpose if you carry or use a firearm, we have USCCA. A local lawyer is only one phone call away as is Bail if you need it.