I am going to smoke (18.5 WSM) 4 full racks of baby backs for the first time, previously only done 1 or 2 at a time. What advice would you give regarding the temp difference between the upper and lower rack? Should I rotate the meat periodically? I have done 3-2-1 and 2-2.5-1 and been very happy with the results but would like to try "No foil" just on the smoker naked for the entire cook. Should I use the water pan or sand etc. etc. It's an important cook because it's my father's b-day and I don't want to mess it up so any and all advice is greatly appreciated. Thanks!