I agree the duck is oily with lots of fat. Thats what makes it so good when you cook it in my opinion. I do mine similar to yours PL, I have also done it where I make slices in the duck and jam garlic on toothpicks into the slots. Then I let it soak like that covered in maple syrup (real stuff so its thin and flows easily) in a ziplock so its always immersed.
Cover it in montreal steak seasoning when I put it in then throw the oil into the maple syrup mixed sauce and keep basting every so often. I usually do two or three at a time though.
Ham takes wicked done like that as well.