Hi Steve,
I was hoping someone with more C&O expertise would chime in, but here's what I can tell you.
On underbodies- Rowa (MRC, Con-cor) used the same underbodies on all three C&O PS cars, as well as on their rendition of the Budd Slumber-coach, so I would speculate that it can only be accurate for 1 of those cars, and may not be accurate for any of them.? I would bet that sometime in the 60s or 70s, MR or MRC probably published plans for those cars, and some of their articles on modeling passenger cars included underbody layouts.? But no guarantees.? Perhaps someone has an index that goes back that far, otherwise it would be a search of hundreds of issues.? You might also, at least for the coach, take a look at the underbody of the Centralia version of the car, if you happen to know anyone that owns one. (Or maybe someone here could take a photo for you?)? You might also want to contact the C&O historical society.
The late Jerry Laboda (the original founder of this group) built the online Passenger Train Photo Index, which is still online at .? If you note, on that page, there is a link that allows you to download your own copy of the files. The online copy at this point doesn't work well (the C&O link not working at all, for instance) but you can download your own copy from the link I posted just above.? There are a number of photos in that collection that show skirts removed, but also a lot of detail on the underbodies.
On skirting- taking a look at my books, photos from the early 50s show skirting on a 10-6 sleeper, and the skirting as shown is quite similar to what is modeled by Rowa, etc.? A photo of Allegheny Club taken in the late 50s on a Santa Fe tour train also still has skirts.? Photos from a book on Chicago in the 60s show all the cars as having skirts (and sometimes fluting) removed.
That's all I could come up with in a quick perusal of my library.? Hope it helps.
Regards,
Tom D.