Adding a shelf may be easy, but you must consider the lose of height above the shelf that you have now and the height above the added shelf. With a added shelf, you will increase the amount of meat that you can put in your smoker, but you may reduce the volume of air flow that flows thru the cooking chamber. The size of the cooking chamber, location of fire box in reference to the the cook chamber, fire box size, intake air placement/volume, Exhaust height/size/location, design of air flow thru the cook chamber. All of this must be considered when building or modifing a smoker. When all of this and more is considered, you will need to learn how to use the modified/new smoker.
