In a skillet, fry bacon until brown. Drain and place in the crockpot. Remove all but a small amount of fat from skillet and saute onions until slightly brown, place onions in crockpot. Cut pork loin and sirloin tip into 1/4" dice and brown with ground chuck in skillet. Drain off fat and add meat to crockpot. Add remaining ingredients except cheese. If you choose to use dried pinto beans, soak in water overnight, discard water, add beans to crockpot and stir. Set crockpot on LOW and cook for 6 to 8 hours. Meat should be very tender. Taste and adjust seasonings. If desired, sprinkle with cheese before serving.