Preheat oven to 350 degrees. In a saucepan, bring water, milk, butter, and 1/2 tsp salt to boil. Remove from heat and stir in flakes. In a bowl, combine eggs, oats, green pepper, onion, pepper and remaining salt. Crumble hamburger over mixture and mix well. On waxed paper, pat mixture into a 12 x 8 rectangle. If adding cheese, lay slices end to end down center of loaf. Spoon potatoes lengthwise down center third to within 1 inch of edges. Bring long sides together over potatoes to meet in center, seal seam and edges. Place seam side down in 13 x 9 baking dish. Bake uncovered for 30-35 minutes then drain. Pour V-8 over loaf and top with ketchup. Bake 18-20 minutes longer, or until meat is no longer pink and meat thermometer reads 160 degrees. Let stand 5 minutes and serve.