I have seen many do this......but it will be a lengthy cook. I don't have a WSM but I read these guys starting at night to get it done on time.
Lately I have been cutting mine into a couple chunks and using my WSK. Shortens my time on the bbq for sure, and I can be sure its done for dinner when I start working around 7 am.
With smaller chunks ( 2 or 3 ) I get more rub as there is more surface area........either way works well, 1 piece possibly will keep better moisture.
Make sure to take lots of pictures.........we might no believe you unless you do......