You can insert an onion or apple into a whole bird to get some inside moisture and flavoring. If you have a Brinkman-type smoker with the water pan, just follow the directions for doing a whole turkey. You might want to get your butcher to cut your turkey in half down the breast if you have a smaller pit or just want half a turkey at a time. Makes it a lot easier to cook on a grill being you have half the thickness to cook. Do most of your cooking bone side down.
Domestic duck is very fat.
The best thing might be just to remove the breast and cook it. Cornish game hens can be cooked whole without a lot of bother due to their small size. Treat them just like you would chicken. We will at a later date try to find some words of wisdom for preparing wild game birds on the pit. There is a lot of fat in the skin of your poultry.