The heating the cast iron pot on the stove is a trick told to me by old hunters in my area, it sounds dangerous to me. This trick was obviously done before furnaces were popular (or available) in campers. Heating the pot transfers the heat from the stove to the pot which makes the entire process more efficient. Your getting the heat from the flame plus the heat from the hot pot/pan. Pretty much the reverse process of a heatsink. I am by no way endorsing this or recommending it but seems this wave 3 idea is similar.