I want to do a chuck roast and ribs soon, but I know cross contamination is always a concern. However the WSM's grates are stacked one directly over the other. is this a concern if i'm doing a chuck roast on one level and ribs on the other? Also is there a preferred setup, should the ribs be on the top rack if it's okay to do, or vice versa? Obviously with poultry it's a no-no but i always assumed Pork and Beef would be fine together. Thanks in advance.