foxtail,
Here's what I use for chicken and Pheasant:
1/2 cup non-iodized salt
1/2 cup brown sugar
1 qt water
Place in brine overnight, then Cook at 375 degrees for 1 hour.
Place in smoker with your choice of Hickory, alder or whatever for 4-6 hours.
Don't know about the duck as I have never smoked one.