Native Kalifornians here. Left Florida in 2013 for Florida. We have a mail forwarding service in Pensacola Fl. American Home Base. They have tons of information on how what when etc. They provide a physical address which helped. Sold our house, already had the RV. Do take your time doing extensive research on the sales tax thing. If you take delivery in Calif you may be stuck.
Hmmm, you might want to fly to Florida to pick up your new RV which will bring revenue to my new state of residence. Then drive it back at your leisure to break it in.