We made Florida our domicile state when we went fulltime. The order we did it in:
1. Got a viable address/mail service. We used Good Sam in Crestview. Escapee's works as well - check insurance rates (car and health) as they vary by county.
2. Once the address was official, we changed our bank account, finance accounts, and credit card addresses to match. It took about three weeks total as we had to wait for a bank statement for proof of address.
3. We titled and registered our car/MH. This was simple for us as we bought new (in Maryland) and had the dealers do it using our new address. Bought insurance on-line during purchase (Progressive.com). Took two weeks (by mail) to receive our permanent plates. Maryland and Florida sales tax were the same so we eliminated transferring issues. Auto insurance prices were also comparable (a little less in FL).
4. Drove to Florida, got our licenses and registered to vote. Took 1/2 an hour. No questions asked.
We 'moved' to Florida in September so we paid income taxes to Maryland for 9 months and nothing to Florida. We did get a deduction for sales tax paid for our RV and car.