Very little is truly "impossible" ...but I don't think it's productive to go down that rabbit hole, because if we do then the entire discussion of evidence becomes meaningless. You no longer have a lighter-skinned perp because he could have used makeup, you no longer have a shape of the face because he could have put cotton in his cheeks, you no longer have a general idea of weight because he could have used foam padding to alter the appearance of weight, you no longer have a general idea of height because he could have used sizable lifts to alter height, and so on forever. IMO it makes for a better analysis to stick with the obvious, which tends to also be where the facts almost always lie. JMO.