HEAT oven to 400°F.
BROWN meat with onions in large skillet on medium heat; drain. Stir in 1/2 cup tomato sauce, zucchini, rice, oregano and basil.
CUT tops off peppers; remove and discard seeds. Pour remaining tomato sauce and water into 13x9-inch baking dish; stir. Place peppers in baking dish; fill with meat mixture. Cover.
BAKE 35 to 40 min. or until peppers are tender. Top with cheese; bake, uncovered, 5 to 7 min. or until melted. Serve peppers topped with sauce from bottom of baking dish.