Is coach NEW.....or already own it?
Are you 65+ with Medicare or under 65 and need Medical Insurance
SD.....easy for FTrs to establish 'domicile' but under 65 medical insurance is Limited at best and Nationwide Coverage non-existent
TX.....easy for FTrs to establish 'domicile' but not sure about medical nationwide coverage options
FL....easy for FTrs to establish 'domicile' and Nationwide Coverage available (not sure of any changes 2019)
SD,TX,FL---no State Incomes taxes
Would need to check on costs of Registrations/Insurance for your vehicles BASED on your driving records and which State is 'domicile'
Escapees is a Mail Forwarding Service that was originally based in Livingston TX but now has services in SD & FL
They have been doing it since 1985 and can be a good resource of actual information
https://www.escapees.com/mail-service/