Mr. Deasy, there appears to be conflict between our respective recollections.
On my "easy days", i.e. few or even no classes and usually Tu and Th, I'd bike it down to the station for a peek at 52 or 53. The NP Sleeper Domes to my knowledge did not have the Dome windows sheet metaled over; somehow I think I would have noticed it.
Now I was "outta there" short of a degree June '65 to raise my right and "do my duty for my country" (I am a U of IL graduate; I knew I'd return to finish up). Who knows, as I don't, how long after the severe '67 IC and elsewhere downgrades, the lease of those Domes continued, or if after I left the scene they did in fact give 'em the sheet metal treatment.
By the time I did have my first and only City of Miami ride Opelika to Chi during Oct '68 (still "in" but CONUS), the Missouri Pacific Coach Domes were in consist - and they indeed were sheet-metalled over. Of course by then the whole train had been badly downgraded; the only Food & Beverage was from a Lunch Counter car that was on the City NO during '62 and still the "de facto Jim Crow" days.
Oh well, I guess from the "Dome" our arborist colleagues could see the tops of the Pine Trees; maybe even tell if it were a "Pitch" or a "Loblolly". To me though, I needed to see a listing of the L&N 6-4-6 car names in the Official Register to know that Pine Trees came in more than one varietal.