A Great Lakes trip from NC is doable in 2 weeks, we did the following in Sept, 2012
Day1, leave NC
Day2, stop at RV Hall of Fame(Elhart), on to South Haven,MI- free night at Waterfront Skate Park parking lot on Lake Michigan shore.
Day3,halfway up Lake MI shore with stop at Silver Lake St Pk to ride DunBuggies on Silver Lake Dunes, night at Manistee Nat Forest, Pines Point CG.
Day4, continue up western MI on Lake MI shore to Sleeping Bear Dune Nat Lakeshore, night at DH Day CG.
Day5, over to Mackinaw City, night at Mackinaw Mill Creek CG.
Day6, up to Sault Ste Marie(Soo Locks), night at Aune-Osborne RV.
Day7, Whitefish Point(shipwreck museum), Tahquamenon Falls, night at Lower Falls CG.
Day 8-9, Pictured Rock Nat Lakeshore, take boat tour, both nights at Hiawatha Nat Forest, Bay Furnace CG-next to PRNL, west entrance.
Day10-17, From here we went on west to Porcupine Mtn St Pk(Lake in the Clouds & Presque Isle), south to Door Peninsular, next to Wisconsin Dells(Duck boat ride), south to Springfield(Lincoln Museum), east toward home.(Total 3200 miles)
Our other alternative return route was:
Day10-16, return to lower MI going down east side(Mackinac Island, Lake Huron, Lake Erie), east to Cedar Point(Amusement Pk), then south toward home.