Pack your Gerbings heated jacket liner for the run North up from the South. When I've done this in Winter it gets cold North of Carolina. Below about 45F I like the Gerbings to kill the chill. Warm gloves are nice too. I've done that run many times. Fun to see the look on the cage drivers. As to the route across from the West, there are bicyclists doing the Southern Tier Route all the time from California to Fla.