From what I read in the Escapees magazine and on their site, you may set up a mailbox for the purpose of having an address where "domicile" type documents would be sent. . . insurance, license plates, voting documents, tax returns, etc. Those documents, once sent to SD, would be forwarded to your mailbox in Livingston. It's an extra stop for your mail. That mail would be sent first to SD, then forwarded to Livingston. All other documents and mail go directly to your mailbox in Livingston.
As far as registering vehicles, etc., you have that all to do on your own. I don't think they have staff to do that for you.
As I understand it, the Florida connection works the same.
We have been using Alternative Resources, now Dakota Post for 10 years and have been extremely happy with them. When we buy a new vehicle, they had a dedicated employee you talk with who walks you through the forms to fill out and then you mail it all to her and she goes down to the BMV and gets your plates, etc., for you. If there is any problem, she will tell you exactly what you need to do. I think the cost for that is about $40, much cheaper than driving there. Voting is simple. . . they can put the absentee ballot applications in your box rather than you writing for one. Easy peasy.
Dale