I ordered a turkey from a turkey farmer and I won't know the exact weight until this afternoon. It's approximately an 18 lb hen. I won't have much time to dry-brine it so I thought if I spatchcock it it would at least be cooked more evenly. I've never spatchcocked so I have no idea what sized pan and rack I will need for an 18 lb turkey. Will a 11" x 17" baking sheet do? Will it be enough to catch the juices? I'm picturing it hanging off the edge and my oven smoking up.