Mysterious car in Rio Grande Southern Story Volume 11

Ok, experts of the Narrow Gauge, here's a question I've wanted to ask for some time because I'm completely stumped.

In the Rio Grande Southern Story Volume 11, there is a photo on page 167 of engine 42 all dolled up for promoting Liberty Bonds. Right behind the engine, there is a flat-roofed passenger car, presumably a baggage car. The caption mentions it as such, but, there is a problem. From what I can determine, by WWI there were no more flat-roofed cars on either the RGS or D&RGW in revenue service.

Based upon Herb Danneman's book, here's the breakdown of all the flat roofed cars.

51-Still in service on the D&RG in 1918, but an Outfit car for many years by this point.
52-Retired by 1899
55-On the ground at Vance Junction 1904
56-Destroyed 1892
57-On the ground at East Mancos 1903
58-On the ground at Starvation Creek by 1903
59-Retired by 1888
100-Heavily "rebuilt" into Business Car K-no longer flat-roofed
101-Heavily "rebuilt" into Business Car P-no longer flat-roofed
102-108-All retired by 1892
109-Retired 1904
110-Heavily "rebuilt" into Business Car X-no longer flat-roofed
111-Original car probably destroyed, heavily rebuilt without flat-roof
112-115-All retired by 1891
116-Heavily "rebuilt" into Business Car R-no longer flat-roofed
117-Sold to RGS as a provision car-was in service as an outfit car till 1914, wrecked and body placed on the ground at Rico (Was it placed on the ground right then?)
150-Sold to Silverton Railroad 1888. Not sure when it was retired, and trucks removed.
E-Retired 1889

From what I can gather, only two cars fit the bill, and both would be strange choices. I doubt it would be the 051 as it was probably pretty ugly looking by this time from being an outfit car for so long, and the car in the photo looks like it has a door near the end of one side, which doesn't match the 150's arrangement, at least while it was a D&RG car.

So, what is this car? Or, is it not from WWI, and really an earlier photo?