Still musing about Clark’s train photo, mostly thinking about the last two cars.
The last car would appear to be something like the 1937 AAR boxcar, a bit taller than the car ahead of it with a corrugated door.
The second to last car is a puzzle. There is no relief to the door, at all, which could indicate that it is a double sheathed wood car with a wood door. The logo on the right side is lower than most roads who placed a (sorta) round logo on the right side (like SP, GN, etc.) CGW tended to have more centered logos. Did they have any DS wood boxcars at the time of the picture?