Preheat the oven to 375 degrees and line a baking sheet with foil.
In a large bowl, mix the ground beef, rolled oats, egg, milk, salt, and black pepper until just combined.
In a small bowl, stir together the crumbled cornbread and chopped onion to make the stuffing.
Shape half the meat mixture into a flat rectangle on the baking sheet. Spread the cornbread stuffing down the center, then top with the remaining meat mixture and seal the edges to enclose the stuffing.
Lay the bacon slices over the top of the meatloaf, tucking the ends underneath.
Brush the barbecue sauce evenly over the bacon.
Bake for 50 to 55 minutes until the internal temperature reaches 160 degrees. Let it rest for 5 minutes before slicing.