An issue is health insurance. If you are on Medicare, you can go anywhere in the US. You can still go to other physicians outside your "local area" otherwise full timers would have to stay in one state.
If you are free to move around, as suggested before the three primary states all have methods used to simplify travel issues. Escapees is based in Texas but has programs they use for Fl and I think they were doing something in SD, but may have stopped that one. Look at all your cost, insurance is usually a big one. Health ins if not on Medicare I have heard the best commercial programs are in FL, Tx, I dont know and SD has decent ratings but limited range of providers.
For me, vehicle insurance was a lot cheaper in SD than Fl , I did not check Tx.
SD does not require any state inspections on your vehicle, so no annual trip back for that. No personal property tax or state income tax. And for a mailing addy for snail mail,
https://www.dakotapost.net/ has worked well. They notify me of incoming mail, scan the envelope or cover and then I tell them IF, when or where I want it forwarded. They will also handle DMV business for a fee.
Escapees and other perform similar services, in the other states.