Of all the theory’s offered out there, Andrew Masons is about the only one I’ve read that actually seems to for a TSBD shooter using a bolt action rifle.
This theory compares favorably with witness like Harold Norman, and the 1st shot at approx Z190? consistent with Willis girl stopping by Z195, and the 2nd shot about Z270 ish then followed by Z313, not only gives a more probable spacing of 6-7 secs required for aimed shots with an MC rifle, but the spacing compares favorably with the 1….2..3 pattern that 2/3 ear witness described.
Additionally the shot sequence beginning at Z190 ish fits in between with Betzner Z186 and Willis Z205 photos which is where they both first heard a shot fired approximately
Therefore , if Andrew’s theory is correct, then any suggestion that the TSBD shooter stood up is improbable as well as unnecessary because at Z195 , the TSBD shooter sitting in a box would be able simply to lean over as (Charles has demonstrated ), and would be able to aim at the JFK limo without need to stand up.
There is an obstacle at Z195 which is the tree foliage, however the shooter if using the scope might have been able to see thru it.
This however , then does bring into question if the scope was out of alignment thus may be why the 1st shot at Z195 hit JFK in the back rather than head.
The only major anomaly in Andrew’s theory (imo) is still what many of us on this forum seem to be observing in the Z224-Z230 range which is the apparent simultaneous reactions of JFK and JC to being HIT by a bullet.
If that’s the case then the 2nd shot in Andrew’s theory being at Z270 ish? must be the missed shot and was this also the shooter still using his scope or had he switched to using iron sights at this point.