I am doing 4 Butts on the large this weekend. I have done them singulary many times with great results. Are they any do's or dont's. Each will be approx 8lbs so I am cooking for 1.5 - 2 hrs per lb regardless of how many butts. Unlike most cooks where its the wife and I this time time I have 40 people coming so I need to make sure these are done on time.