I am planning on building a smoker on a small trailer. I want to do a reverse flow with two racks in the main chamber and four 16X22.5 in the box above the Firebox with two four inch stacks exciting. The firebox is going to be 1/4 and the box above will be 3/16 thick. This is a sketch of the basic dimensions. Any advice or suggestions are appreciated. As it turned out the tank was 24" dia when I picked it up. the door is 49" long by 21". Does anyone see any issues with flow or temp control with the end box being on top of the firebox?