In nonstick skillet, cook bacon in 2 batches until crisp, 10 minutes per batch. Remove from skillet to plate. Drain fat; wipe skillet with paper towel.
Coat bottom of flour tortilla with nonstick cooking spray. Place, coated side down, on flat work surface. On half of tortilla, place 2 slices bacon, 2 tablespoons cheese and 2 slices tomato. Spread other half with 1-1/2 teaspoons mayonnaise. Fold tortilla over. Repeat with remaining ingredients to form 8 quesadillas.
Coat skillet with cooking spray. Heat over medium-high heat. In batches, heat quesadillas through, about 2 minutes per side.