I am building a reverse flow smoker out of a propane tank I need help with the measurement. How big of a fire box do I need I was thinking about useing a tow motor tank but don't know if it will be the right size. Where do I put the baffle I was thinking about cutting a 3 or 4 inch pipe in half and weld it in the middle of the baffle plate and make a trough for the drippings to drain to the drip tube. How big should the opening be at the fire box and at the other end for the smoke to go in the cooking chamber. What size of pipe should I use for my smoke stack and how long should it be? The tank is 73" long and 132" round. I was going with one door but also was thinking I might put one one both sides. I want a lower and upper cooking racks.