Mix ground beef with seasoning mix in large bowl until well blended. Shape beef into 6 oblong patties, about 6 x 3-inches each. Whisk together barbecue sauce and dressing in small bowl; set aside.
Spray grate of outdoor grill and utensils with grilling spray. Preheat grill to medium heat. Grill patties 5 minutes on one side or until juices begin to appear on surface. Turn patties over; top each with 3 slices bacon. Cook about 4 minutes longer; top each patty with 2 triangle pieces of cheese, overlapping to cover patty. Remove patties when cheese begins to melt.
Spread barbecue-dressing mixture on bottom of each roll. Add a lettuce leaf. Place cooked patty with bacon and cheese on lettuce. Spoon additional barbecue-dressing mixture over cheese. Sprinkle with fried onions, if desired. Serve immediately.