Well........you need a legal address to use as an official location for residency in order to get Vehicle Ins, DLs, Vehicle Tags/Registration, Voting, MEDICAL INS., Wills/Trusts and MAIL ----same stuff you had with a S&B Address
Many Full Timers pick a 'domicile' state and then use a Mail Forwarding Service in that state that is in business of providing that legal physical address and handling all your mail.
Some folks just use a UPS Store mailbox etc.
But you will need one for that legal physical address.
SO what state is your 'domicile' going to be.then goggle mail forwarding service
SD has numerous, FL has several, TX majority use Escapees
ALL of them are GOOD---it's what they do and RVs wouldn't continue using them if they messed things up.