WOW again. I think that your work is going from strength to strength; same applies to the historical research.
Seeing those small upper berth windows reminded me that I have one UP car that has them. It's an MTH car that I think came as part of a Dealer Appreciation Program set when the PS2 version of MTH's monster DDA40X was first issued, which I think was about 10 years ago. This is the only streamliner car I have with what are "clerestory" windows but I was too lazy/unmotivated before now to look up the car and see what they were for. As you can see, this is named/numbered Green River #1602:
As you can also see as a result of the interior lights being on, in the model the upper windows are in fact molded straight through the body shell although I can't see that there are berths represented behind them.
This car is listed in the UP records as a sleeper and I think that the model represents it in an early and maybe the "as built" configuration. The car, which seems to have been rebuilt extensively at least twice, is still in the UP Historical Fleet but the upper widows are gone and the lower windows have been totally reconfigured. Details of the current version of this car are here: https://www.up.com/aboutup/spe..._equipment/index.htm
I was particularly interested in the Pullman Travel Comfort poster you photographed. That must be very rare; I certainly have not seen an image of it before and I have researched a literally huge number of streamliner posters.