To make Makeshift Pizza, you will need a frying pan as large as the pizzas you will make. Bake the pizza crusts the night before or purchase round pizza-crust bread from the store. Pack them in the frying pan to protect them from breaking. Bring along a can of tomato paste for each pizza and a mixture of Italian spices. Bring your favorite shredded cheeses—mostly mozzarella—and whatever pizza toppings you prefer. (You can find sliced pepperoni that does not have to be refrigerated in most grocery stores.)
When you are ready for lunch, build a small fire. A few one-inch diameter dead pine branches make the perfect fuel. Let the coals burn down.
As the fire is burning down, spread the tomato paste on the crust in the pan, sprinkle with Italian seasonings, and prepare the pizza with the toppings. Cover the pan tightly with aluminum foil.
Scrape the coals away and nestle the pan down into the warm bed. If there is too much heat, the crust will burn. Place a hot stick or two on top of the foil. Let the hot bed warm the pizza through and until the cheese is melted. You may have to recharge the bed with reserved hot coals. When the cheese has melted and is bubbly, the pizza is ready.
Makeshift Pizza only works the first day out unless you have some way to keep the perishables cold. (A good snow bank will do.) And the ingredients are a little heavy to be packing far.