Heat oven to 375°F. Rub turkey with half the oil, 1/4 teaspoon salt, and pepper; place in a small roasting dish. Toss tomatoes with remaining oil and salt; place cut-side up on a separate sheet.
Roast turkey 45 to 55 minutes until center reaches 165°F. Roast tomatoes alongside 40 to 50 minutes until soft and lightly browned. Rest turkey 15 minutes.
Bake bacon on a clean rimmed sheet in the hot oven 15 to 20 minutes until crisp. Drain on paper towels.
Once cool enough, thinly slice turkey across grain. Spread in a shallow container with a little roasting juice. Promptly refrigerate turkey and tomatoes within 2 hours of cooking; chill at least 1 hour.
Broil cut bagel faces 1 to 2 minutes; cool. Mix mayonnaise and Dijon; spread on both cut faces.
Layer bottoms with dry romaine, turkey, two tomato halves, and two bacon slices each. Close and halve; refrigerate until serving.