SPREAD tomatoes onto bottom of parchment-lined half-sheet pan; drizzle with oil. Sprinkle with salt and pepper. Bake in 250ºF standard oven 1 hour.
FOR each serving: Spread 1 Tbsp. mayonnaise onto each of 2 toast slices. Cover 1 toast slice with 1 lettuce piece and 4 tomato slices; top with second toast slice, second lettuce piece and 3 bacon slices. Cover with third toast slice. Secure with long sandwich picks; cut sandwich diagonally into 4 triangles.