I apologize for coming across as lazy, but let me explain:
I did as instructed: downloaded the files, extracted them, and dropped them into the data folder as was listed. This was after you said to do it all manually. Wasn't using MO2, I was ONLY using that, and the ArchiveInvalitdationInvadlitated BSA. Then, as per normal, renamed the appropriate mesh and renamed it upperbody.nif, in this case the non-erect nude mesh. Then started up the game, and when I was able, COC'ed to Aerotech Office Park to check if the texture issue was still there for the ghoul Bert Gunnerson, as the Merc Grunt is almost identical to the Surgeons outfit, at least in the sense that they both have sleeves.
The texture was fine. Killing him and then stripping him revealed that the nude mesh was working perfectly for the ghoul as well. The same could NOT be said for the normal human male mesh, resulting in black underwear.
Did I miss anything from the previous instructions?