Preheat the oven to 450 degrees F. Drizzle the olive oil in a 10-by-15-inch baking dish or on a rimmed baking sheet. Place the balls of dough side by side in the baking dish and pinch the edges together to make one large piece of dough. Press and stretch the dough so it fills the dish. (If using a baking sheet, press and stretch the dough into a 10-by-15-inch rectangle.) Spread the crushed tomatoes over the dough, leaving a 1-inch border around the edge. Top with the red pepper flakes, cheese, sausage and green pepper. Bake the pizza until the crust is golden brown and the sausage is fully cooked, 25 to 30 minutes. Let cool slightly, then cut into squares.