Artic, you mentioned a slow cooker and if I'm reading you correctly, you would prefer a dish that doesn't require lots of work. You could try sub ground chicken/turkey in place of the beef. I'm reluctant to put sour cream in a slow cooker unless it's close to the end of cooking time. If in doubt, go with tomato sauce.
Crockpot Stuffed Peppers
6 med. to lg. peppers
1 1/2 lb. ground chuck
1 med. onion, chopped
1 (16 oz.) can tomato sauce
1 (16 oz.) can whole tomatoes
1 (8 oz.) container sour cream
Minute rice (2 servings), make according to directions on box
Clean the inside of peppers and cut off tops. Mix ground chuck, onion, whole tomatoes drained squeezed into ground chuck, pepper, and seasonings of your choice and rice (made according to the directions on the box). Put ground chuck mixture into raw peppers. Place peppers into crockpot. Mix the can tomato sauce and sour cream together. Pour mixture over the stuffed peppers. Set crockpot on high and cook for about 5 to 6 hours or on low 8 to 9 hours.
I would sprinkle some shredded mozzarella over the tops of the peppers at the end of cooking time. Just until it melts. Or fill peppers with frozen/thawed hashbrown (cheese)mixture.