Heat grill to medium heat.
Mix meat and 2 Tbsp. dressing; shape into 8 thin patties. Combine remaining dressing and bacon. Spoon onto centers of 4 patties; top with Singles quarters and remaining patties. Pinch edges together to seal.
Grill 7 to 9 min. on each side or until burgers are done (160°F).
Fill buns with lettuce, burgers and tomatoes.