I was wondering if someone could help me out? Im not sure if I should be building a j tube stove or a 6 inch RMH. Currently building a 200 sq ft , 4ft in the ground, the roof is carpet, a layer of 6 mil plastic and finally some chicken wire covered with a thin layer of concrete. We have a south facing window thats 6 ft x 5 ft . Winter lows can get as low as 10 degrees. I appreciate your opinions. Thank You !