I am building a upright, insulated smoker. I have never seen one of these units up close and personal so I am in need of a little help here. It is going to be approximately 2 ft x 2 ft x 4 feet high. I have a propane burner that is 40,000BTU capable to mount in the bottom. I am going to use a steel mixing bowl for my smoking chips and a metal serving tray for water and the drippings. What I need to know is how far away from the top of the burner should the bottom of the chip bowl be so that it creates enough heat to get the chips smoking?