In a large bowl, combine the first six ingredients. Transfer to a double thickness of greased heavy-duty foil (about 18 in. square). Dot with butter. Fold foil around potato mixture and seal tightly. Grill, covered, over medium heat for 15-18 minutes on each side or until potatoes are tender. Carefully open foil. Sprinkle the bacon cheeses over potato mixture. Grill 3-5 minutes longer or until cheese is melted. Open foil carefully to allow steam to escape.