OK so I want to undertake a vertical smoker build. I have a large propane tank with lots of room. I am hoping to be able to make this a two or three rack vertical so I can cook lots at once, but I have many questions that I cant seem to find the answers to, they are as follows; 1)To separate the firebox from the cooking chamber, should I put one large hole in the middle of the diffuser plate, or several? I intend to use charcoal minion method. 2) I have looked for a vertical smoker calculator to no avail, not sure if it is not needed due to being a vertical, but if an UDS can cook circles around a COS (which I have), do I need to be overly concerned about Things like exhaust diameter and length. I can imagine that the percentage factors are fine for firebox size to cooking chamber, but what of a single hole in the diffuser plate. Can it be tuned to draw heat into the cooking chamber? 3) the tank will have a domed top. I intend on dropping the exhaust to the level of where a "flat top" would be if no dome. Is this necessary? My thinking is to maintain temps evenly in the dome before heat is forced into the exhaust. 4) Is there anything that I need to consider before getting started ie, single door/double door? Here is a pic of the tank. It is three feet across, I think I only want the smoker to be about 4-5 ft tall. (including the firebox) Steel is 5/16 thick. Somewhere there is a horizontal lover shaking their head! Sorry!