Cook bacon and let cool so you can crumble up into smaller pieces (or use pre-cooked bacon crumbles). Cook potatoes in a large pot of salted water.  Bring to a boil then simmer, covered, 20-25 minutes or until tender. Drain and cool potatoes.  Cut into bite-sized pieces and mix with 2 cups mayonnaise. Mix bacon, cheese, and chopped green onion to remaining 1/2 cup mayonnaise.  Add to potato mixture by gently combining so potatoes don’t fall apart.  May add salt and pepper to taste. Top with bacon crumbles and chill before serving.