Lots of people who aren't boaters get mail in more than one state. Think of people who own summer homes, etc. However, some states, especially those with
income taxes (which Florida does not have), scrutinize these addresses more carefully to see if you might possibly be working in the state and not paying tax on the
income earned there. Having said all that, it is simpler when dealing with officialdumb to have everything go to one legitimate looking address that isn't a PO Box or other obvious mail service. For some things, like a driver's
license, most states won't take anything but a street address verified through the Postal Service. However, apparently SBI says that these things can be done through them if you wish to move your
license to Green Cove Springs, FL. If you don't intend to move your
legal domicile to Florida I think it is simpler and cheaper to just keep your
current address. I find that I can whittle down the important things that come via mail to a very few as most bills, etc. can be sent via
email. The ones I couldn't get rid of were my life
insurance bill (they only mail and only accept checks), my driver's licenses (renew every 8 years), my income tax address (but you can file and receive refunds electronically), my CG
documentation, my FCC
radio station license, and a couple of others. Something arrives periodically in the mail that is a surprise, so it is good to have someone there who can take care of something important.
By the way, it is usually so expensive and so slow to get mail in many places cruisers go, like much of the
Caribbean, it just isn't worth it unless someone is flying in to see you and can carry the mail. I find it is just about critical that someone "back home" can take care of an important bill for you, etc. It is generally pretty easy and
cheap to call from almost everywhere, so it is fairly easy to give instructions to your home base person. If you're staying within the
USA it is entirely possible to do it all yourself and get mail forwarded at reasonable intervals.