Thats a curious statement.
You say that they would not usually do a 1x1x1(one front, one middle, and one rear), which would be as we see in the photo instead with 2 and 1 on the rear.
However you state that if 4 engines were used they would infact use the midtrain and be 1 on the point and TWO midtrain, and one on the rear.
I think I have seen photos of this on Marshall Pass, but not on Cumbres.
(1) Why would two engines be okay midtrain, but not one on a 3-engine train?
(2) Did you ever see pics of 4 engine trains like that on Cumbres with the bigger K engines?
Greg