woodchucks do not "preen" themselves with any oil (such as water-loving mammals such as beaver, muskrat, mink, etc) and their hair is not especially hollow, so in my experience it has no special floating characteristics. 'chucks are common to the point of being pests in most areas of the east, with similar creatures across most of the other parts of the US. Would be best to go shoot one yourself and give it a try, or at least pick up a fresh road kill.