Shape Beef Into Three 1/2-In.-Thick Patties. Grill, Covered, Over Medium-Hot Heat For 5 Minutes On Each Side Or Until Meat Is No Longer Pink. Meanwhile, Combine Ketchup And Mustard; Spread Over The Crust To Within 1 In. Of Edge. Sprinkle With Lettuce; Top With Tomato. Sprinkle With Salt And Pepper. When Beef Patties Are Cooked, Cut Into 1/2-In. Pieces; Arrange Over Tomato Slices. Top With Onion, Pickles And Cheeses. Place Pizza On A 16-In. Square Piece Of Heavy-Duty Foil; Transfer To Grill. Grill, Covered, Over Indirect Medium Heat For 12-15 Minutes Or Until Cheese Is Melted And Crust Is Lightly Browned. Remove From The Grill. Let Stand For 5-10 Minutes Before Slicing.