Heat gas or charcoal grill to medium heat. Cut 14 x 14-inch heavy duty foil; spray with cooking spray. Place dough on foil; starting at center, press dough to 12-inch round. Place dough on grill, foil side down. Cook, uncovered, 3 minutes or until bottom of crust is light golden brown. Remove from grill.
Using wide spatula, flip crust over so uncooked side is down. In small bowl, combine chicken, barbecue sauce and chili powder; mix well. Spread chicken evenly over pizza crust. Sprinkle with cheese, onion and bell pepper.
Place pizza onto grill, foil side down. Cook, covered, an additional 3 to 4 minutes or until crust is golden brown and cheese begins to melt.