Preheat oven to 350°F. Heat 1 tbsp olive oil in a small skillet over medium heat. Add onion and sauté until soft and translucent, adding garlic in the last minute, 5 minutes. Remove from heat and set aside.
On a large sheet pan, arrange the sweet potatoes in an even layer leaving space for the meatloaf. Drizzle with olive oil, rubbing to coat potatoes on all sides. Sprinkle with 1 tsp salt, dried thyme, garlic granules, and 1 tsp black pepper.
In a large bowl, combine the ground beef, ground pork, quick oats, eggs, tomato juice, sautéed onion, salt, and pepper. Mix until combined and all the ingredients are well mixed together, showing no individual streaks.
Place the prepared meatloaf on the large sheet pan, shaping it into a large loaf. Place in the preheated oven and prepare the ketchup topping.
In a small bowl, combine the ketchup, honey, and mustard. Whisk to combine.
Once the meatloaf is browned and reaches 150°F, about 40-50 minutes, spread the ketchup mixture over the top and return to oven to caramelize, 15 minutes. Remove from oven and cool 10 minutes before cutting.