I'm more worried about the angles taken from the photos. As these were taken by fans, this meant their location and positions aren't fixed, and therefore can be anywhere and varying. Even if they did take it from the same angles, now the burden lies on the J-20. It can also be anywhere and not necessarily the same spot for both photos. It may not be at the same place at it was yesterday. Even if it is the same location that it parked, there are also no guarantees if it was slightly closer to the camera today than it was yesterday.
Lastly, the same goes to the truck. it can be slightly closer to the cockpit today than yesterday, and all that is sufficient to cause misreadings of distances between the shots, the angles, and the sizes of the objects.
Unless everything else in the environment were held constant, it is no controlled setting, therefore it's much harder to compare, and no guarantees of what we'll receive.