My road trip duck when I have to eat it to stay in my possession limit.
I use Teriyaki baste and glaze over each duck breast half. Not the sauce or marinade, its the sticky gooey stuff. I Cook it long enough to caramelize on the meat. I like to sprinkle it with coarse ground black pepper just before or while placing on grill. Cooked over mesquite, hardwood, or charcoal preferred. I have put the duck in a ziplock covered with the glaze for 12 to 24 hours as a marinade or used it right away. Since it caramelizes on the meat, it really does not seem to matter other than time saving having it ready for the grill in advance when coming into camp from an evening hunt.
I also like to cut the breasts into 3 strips per breast half and place in a ziplock in the cooler. Liberally add some Zesty Italian Salad Dressing in with the meat as an overnight marinade, then when ready to cook, wrap a full piece of bacon around the length of each strip held by toothpicks. Add sliced pickled or cut peppers of your choice under the bacon wrap if you like, then grill till the bacon is cooked to your tastes. The duck will be done well enough when the bacon is done.
Both are good for Divers and Mergansers in that the first one ends up tasting like Peppered Teriyaki Jerky and the second one like Bacon. Best served with Steaks and Eggs. Pictured with two filleted Hooded Merganser breasts.