Thanks for all the replies!
Our plan is to sell our house and go full time in the RV. I figure there's no way around California getting it's cut of that. What I'm trying to avoid is paying CA state sales tax on the RV I buy. I'll probably buy from Kansas RV but will be a resident of Florida. I'm trying to time things such that I leave California (whether the house is sold or not) and set up domicile in Florida. I won't have place to live until I pick up the 5th wheel from Kansas RV.
So is it better to set up domicile in FL first? Can I do it on my way to pick up my RV in Kansas?