Place the rice and beans in a mixing bowl. Remove the tops from the peppers and discard the seeds. Blanch the whole peppers and tops in a pot of boiling water for 5 minutes. Remove and drain.
Heat the oil in a medium skillet and sauté the onion for 3 to 4 minutes. Add the sweet corn and sauté 1 to 2 minutes. Place onions and corn in the mixing bowl with the rice. Add the drained tomatoes and mix thoroughly.
Preheat the oven to 400° F. Stuff each pepper with the rice mixture and place in a casserole dish. Place the tops on the peppers. Combine reserved diced tomato liquid, crushed tomatoes, water, and salt. Pour into the baking dish. Cover the dish and bake for 45 minutes to 1 hour or until the peppers are tender. Remove tops the last 15 minutes to brown. Spoon some of the tomato sauce over the peppers before serving.
Per serving - 172 calories, 3 gram fat (16% calories from fat), 7 gram protein, 31 gram carbohydrate, 7 gram fiber, 0 milligram cholesterol, 685 milligram sodium