JohnM
Thanks John, it appears to me that the photo of the actual sniper's nest was taken after the boxes had been moved for fingerprinting and then put back. And it appears to me that they positioned them closer to the center of the window than they originally were. The photos of the reenactment in Max Holland's mock-up, with the guy kneeling, don't include the box that the sniper was sitting on. My contention is that that box would be in the way of his lower legs and feet in that kneeling position. Here are a few photos to illustrate my point.
This first one shows a top (plan) view of the sniper's nest. The box he was sitting on is about 16.5" from the south wall, as indicated in Day's testimony. The 3 boxes just inside the window are positioned closer to the east than in your photo. This agrees with the Dillard telephoto photograph taken seconds after the last shot. The result is that there is very little room between the sitting box and the other boxes for someone to kneel without some interference.
This one includes the sniper sitting on the box and leaning forward. It is the position that is used for the view from Brennan's position. If the sniper sits straight up he is out of view from Brennan's position. And the sniper has a view of all three of the positions of the limo for shots at: just before Z133, Z225, and Z313 without moving much at all.
Finally, Max Holland says in his program that the box the sniper was sitting on was in about the position in this photo. However it was actually much closer as I have shown above. And Max appears to be sitting on two boxes, so he was much higher than the sniper.