Combine the vanilla wafers, bourbon, maple syrup, and half of the pecans in the bowl of a food processor. Process until smooth-ish, about 45 seconds. Using a small scoop, or simply your fingers, shape thumb-sized pieces of the dough into balls about half as big as a golf ball (really, size is up to you). Place the remaining finely chopped pecans in a plastic bag. Add the bourbon balls, one by one, gently pressing the chopped pecans into the sides until they adhere. Top each with a pecan half, if you like. Transfer bourbon balls to a cookie tin and allow to mellow for 1 week or so.