Cardboard Oven
Put aluminum foil everywhere inside a carboard box that is 2 foot square along inside walls cut a hole at the bottom of box. Get charcoal nice and white then place about 6 of them in the middle of the hole this will get the inside the box around 350 degrees. I always use a meat thermometer so I can control the temperature. I cooked frozen pizzas this way i even baked cakes this way while camping primitive. It freaks people out when you can bake a cake or roast when the thermometer temperature stays around 350 degrees when it starts dropping temperature add couple coals to bring it back up.