Preheat the oven to 375°F (190°C).
In a large mixing bowl, combine the ground beef, ground pork, breadcrumbs, milk, ½ cup barbecue sauce, diced onion, chopped bell pepper, eggs, garlic powder, smoked paprika, salt, and pepper. Mix until well combined.
Press the meat mixture into a loaf shape and place it in the center of a baking sheet. Drizzle additional barbecue sauce on top of the meatloaf.
In a skillet over medium heat, boil the sliced potatoes until tender (about 10-12 minutes) and drain.
In the same skillet, combine the boiled potatoes, sour cream, ½ cup shredded cheddar cheese, melted butter, garlic powder, onion powder, salt, and pepper. Mix gently to coat the potatoes well.
Spread the potato mixture evenly in a 9x13 inch baking dish.
Place the meatloaf on top of the potato mixture in the baking dish.
Bake in the preheated oven for about 45-50 minutes, or until the meatloaf reaches an internal temperature of 160°F (70°C) and the potatoes are bubbly.
In the last 10 minutes of baking, sprinkle additional cheddar cheese on top of the potato casserole for added flavor.
Let it cool for a few minutes before slicing the meatloaf and serving.