I would do a search on the computer for mail forwarding services in FL or S Dakota.  Those companies will help you establish your residency and give you a street address that is legal to use on your drivers license, taxes and other things that need a street address.  They will also give you a mailing address to use and will forward your mail to you when you request it.  You do not have to live in the state, but would be considered a state resident.   There are many companies in each of these states and no state income tax.