Cut the tops off the peppers. Remove and discard the stems, then finely chop the tops; set aside. Scoop out the seeds and as much of the membranes as you can. Place the peppers in a microwave safe bowl, add ½ cup water and cover with plastic wrap. Microwave until just beginning to soften, about 12 minutes, then uncover and set aside. Preheat the oven to 450˚. Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add the sausage and cook, breaking it up with a wooden spoon, until cooked through, about 6 minutes. Remove to a plate. Add the remaining 1 tablespoon olive oil to the pan. Add the tomatoes, red onions, garlic, Italian seasoning and the chopped pepper tops and cook, stirring, until tender and lightly browned, 10 to 12 minutes. Season the mixture with salt and pepper and stir in the sausage and rice. Taste and adjust the seasoning. Place the peppers upright in a baking dish just large enough to hold them. Fill with the rice mixture and bake for 10 minutes. Sprinkle with the cheese and continue baking until the cheese is browned in spots, 10 to 12 more minutes.