First, welcome,
To start answering your questions. No, most RV parks do not allow commercial endevors. And playing music for pay would probably fall into that catagory.
Next, your house actually appreciates unless you totally trash it. An RV, ANY RV is a depreciating asset. There is no way it will be worth any more than the day you buy it. Same for tow vehicles. Living on the road, excluding food and clothes is going to cost you anywhere from 1500 to 3000 a month even trying to live on the cheap. Add in maintenance costs and unless you have a decent steady income you could very well wind up living hand to mouth in WalMart parking lots. That does not sound like a lot of fun to me. Instead, maybe you need to relocate out of CA to a state more cost effective and start following your musical dreams.