You never want to smoke a turkey that is filled with stuffing. It will take too long to cook, and might be unsafe to eat. The stuffing will prevent the inside of the turkey to come up to safe temperature quickly enough.
Make the stuffing on the side, and then pack it in the smoked turkey after it's done, just before serving it. There are lots of great stuffing recipes on the net. I like oyster cornbread stuffing myself.
