Step 1: In a large bowl, combine the ground beef, ground pork, bread crumbs, milk, egg, garlic powder, onion powder, salt, and pepper. Mix thoroughly but gently with your hands until just combined, being careful not to overmix.
Step 2: Lay out a large sheet of parchment paper or plastic wrap on a clean surface. Press half of the meat mixture onto the paper, forming a rectangle roughly 8x10 inches.
Step 3: In a separate bowl, combine the shredded cheddar, mozzarella, and pepper jack cheeses. Spread the cheese mixture evenly over the meat rectangle, leaving a 1-inch border around the edges.
Step 4: Carefully form the remaining meat mixture into another rectangle of similar size and place it over the cheese layer. Pinch and seal the edges of both meat layers tightly to completely enclose the cheese, forming a stuffed loaf.
Step 5: Arrange the 6 slices of smoked bacon over the top of the meatloaf, overlapping slightly, to create a bacon weave or simply lay them side by side. Tuck the ends under the meatloaf if desired.
Step 6: Preheat your smoker to 225-250°F (107-121°C). Place the bacon-wrapped meatloaf directly on the smoker grates or on a wire rack set inside a baking pan.
Step 7: Smoke for 2 hours to 2 hours 30 minutes, or until the internal temperature of the meatloaf reaches 160°F (71°C) using a reliable meat thermometer. If you desire a crispier bacon, you can increase the smoker temperature to 300°F (150°C) for the last 15-20 minutes, or finish it under a broiler for a few minutes, watching carefully.
Step 8: Once cooked, remove the meatloaf from the smoker and let it rest for 10-15 minutes before slicing. This allows the juices to redistribute, ensuring a tender and moist meatloaf. Slice and serve hot!