Preheat oven to 350 degrees F (175 degrees C). Line a 9x13 inch baking pan with aluminum foil.
In a large bowl, mix the beef, onion, green bell pepper, celery, eggs, soy sauce, and ketchup. Season with basil, parsley, oregano, garlic powder, and 2 teaspoons pepper. Mix in 1/2 cup oats. Gradually mix in remaining oats 1/4 cup at a time until the beef mixture is firm but not stiff. Transfer to the prepared baking pan, and form into a loaf shape.
In a small bowl, mix the brown sugar, ketchup, brown mustard, mesquite smoke flavoring, 1/2 teaspoon pepper, and paprika. Drizzle evenly over the meat loaf.
Bake meat loaf 1 hour in the preheated oven, or to a minimum temperature of 160 degrees F (72 degrees F).