Are you considering selling the PA house and buying in FL, or just getting a FL-based mail service? Owning a home in FL varies widely in cost, depending on whether it is in one of the South Florida winter meccas, a large metro area, or one of the more rural towns and cities on central & northern FL. Rural area property taxes are low and no state income tax, so it can be rather cheap.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC