Heat grill. In large bowl, combine ground beef and bacon pieces; mix gently. Shape into 8 (1/2-inch-thick) patties. Make slight indentation in center of each patty.
When ready to grill, place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 13 to 15 minutes or until thoroughly cooked, turning once. During last 1 to 2 minutes of cooking time, place buns cut side down on grill; heat until toasted.
Place toasted bottoms of buns on large serving platter. Top each with lettuce. While patties are still on grill, sprinkle each with seasoned salt; top each with slice of cheese. Place patties on lettuce-lined buns. Immediately top each with 1 teaspoon barbecue sauce and 1 onion slice. Cover with top halves of buns.