1. Cook bacon in a large skillet over medium heat until crisp. Remove bacon from pan. Add oil and onion to drippings in pan; cook 15 minutes or until onion is browned and very tender, stirring occasionally. Add 3 tablespoons bourbon, vinegar, and 1/4 teaspoon salt. Cook 2 minutes or until liquid almost evaporates, stirring constantly. Remove mixture from pan. Cool 5 minutes.
2. Combine remaining 2 tablespoons bourbon, ketchup, and next 7 ingredients (through onion powder) in a small saucepan. Bring to a boil, stirring frequently. Reduce heat; simmer 5 minutes or until sauce thickens. Remove from heat.
3. Preheat grill to medium-high heat.
4. Coarsely chop 3/4 cup onion mixture; stir into beef. Divide beef mixture into 6 equal portions, gently shaping each portion into a 1/2-inch-thick patty. Press a nickel-sized indentation in center of each patty. Sprinkle evenly with remaining 1/4 teaspoon salt. Place patties on grill rack coated with cooking spray; grill 4 minutes on each side or until desired degree of doneness.
5. Spread each top and bottom bun half with 1 tablespoon sauce. Place patties on bottom halves; top each patty with 1 tomato slice. Divide remaining onion mixture evenly among servings. Top each serving with 1/2 bacon slice and top half of bun.