Wow, I thought I had alot of meat on my 2 18s for the fourth...I had 2 10 lb butts on one and another 10 lb butt on the bottom grate of the other one...I used the top grate of the second one to smoke sausage and then I put the sausage in some beans and smoked the beans...
good luck...looks like you have it all figured out...don't forget to post final pics