1. Preheat grill to medium-high heat.
2. Gently combine first 3 ingredients and 1/2 teaspoon pepper in a large bowl, being careful not to overmix. Divide beef mixture into 8 equal portions; gently shape each portion into a 1/4-inch-thick patty, taking care not to pack mixture down.
3. Arrange patties on grill rack coated with cooking spray; cook 2 minutes on each side or until desired degree of doneness. Top each patty with about 1 tablespoon cheese during last minute of cooking. Lightly coat cut sides of buns with cooking spray. Place buns, cut sides down, on grill rack. Grill for 1 minute or until toasted. Spread about 1 teaspoon mayonnaise on bottom half of each bun; top with 1 patty. Top each slider with 2 pickle slices, 1/2 lettuce leaf, and 1 tomato slice; sprinkle evenly with remaining 1/4 teaspoon pepper. Arrange bacon pieces evenly over tomato. Top with bun tops.