Pulling a 38' 5th wheel for the last 3 years I take: I-79 south to Rt 19 south. 19 is 4 lane w/a few stop lights but is a more direct route. I-77 south to I-485 beltway around Charlotte. Pick up I-77 again south around Columbia to I-26 east over to I-95 south. This gets you into Florida. I cross over 301 to I-75 south into Ft Myers. Not sure what your best route to Okeechobee is once into Florida......