I fit 12-14 pound packers on my 18.5 WSM all the time. What I do is wrap some HD foil around both the handles and spray them with some Pam. Hold the brisket under the middle and kind of "tuck" the two ends into the handles. The brisket will kind of fold part way and should be fine.
Eventually it will shrink and will fit without having to tuck it.
“If you don’t know who I am, then maybe your best course would be to tread lightly.”
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