How about you do trip A and include a stop at Michigan's Adventure? It will be on your way from Holland to Sleeping Bear Dunes. If I am not mistaken there is a camping resort very close to the park. You could also move to Hoffmaster or Muskegon State Park to be closer for that day.
Michigan's Adventure probably isn't as grandiose as Cedar Point, but they have some good roller coasters and a great water park. Lines probably would be shorter than Cedar Point. The park is actually also owned by the same company that owns Cedar Point.
