Grease your dutch oven. Get your campfire going and prep it so there is eventually a nice bed of hot coals to place your dutch oven on.
Cut the tops off of the peppers. Remove the seeds from the main part of the pepper, and set them aside. Trim the remaining pepper off of the pepper tops. Chop and reserve for stuffing.
Saute the onion in olive oil until translucent. Add garlic, mushrooms, and chopped peppers. Cook until vegetables are softened, about 5 minutes. Stir in the veggie meat and cook for a few minutes more. Mix in the rice and about half the can of tomato sauce. Season with salt and pepper.
Place the stuffing inside of the peppers and then into the dutch oven. If you have any additional stuffing, you can put it around the peppers (just make sure you greased your dutch oven well).
Add the ketchup to the remaining tomato sauce and stir to combine. Spoon some of the tomato sauce mixture on top of the stuffed peppers. Sprinkle the peppers with cheese.
Place dutch oven hot coals, making sure it is stable and level. You may have to shift some of the coals around, or add a rock under the dutch oven to get it just right. Cook the peppers until they’re softened and the stuffing is heated through.