1. Heat oven to 400 degrees. Cut bread loaf horizontally in half. Cut bread halves crosswise in half to make 4 pieces (to fit on a cookie sheet). Arrange on large ungreased cookie sheet.
2. Cook beef and onion in 10" skillet over medium-high heat, stirring occasionally, until beef is brown; drain. Stir in pizza sauce. Spread beef mixture over bread. Sprinkle with tomato, bacon, and cheese.
3. Bake 12 to 15 minutes or until pizza is hot and cheese is melted.