"Largest collection of oldest living things"
Hey! I resemble that remark!
We live in Florida and will be using our son's address. If I recall, you will need some sort of proof that you live at your friend's address to register your vehicle - utility bill, etc. I could be wrong. We aren't expecting a problem because we already live here, he is family and parents moving in with children is a plausible situation.
There is no sales tax on most food items and drugs. If you are fulltimers, you won't be buying much else. Where would you put it? Welcome to our state.