In a few weeks I'm going to cook a whole hog for my brothers graduation party. Now I've done a little research and I'm going to make a cement block pit lined with aluminum to reflect heat on the bottom and the sides, and a sheet of metal to put on the top. Now I was thinking about how to get a thermometer so I could have some idea of temp inside. Now I see a lot of people with a thermometer with a wire outside the smoker with the thermometer stuck in a potatoe. What does the potatoe do? any ideas on a thermometer set up, or on the whole pit for that matter?