Hi Dave:
This is a good question. I have look at lots of photos looking at the Items you have listed and I have tried to stay with the the standard factory camo planes. I am finding some tone differences on some of the photos.
Here is the underside of the top wing aileron horn. This look to be the same color as the undercoating -blue.

(Photo from Taz) The top of the horn looks to match the white from the national insignia white field.
Here is the fuselage holders. These look darker then the blue so I don't know it these are black or not. How dose light gray show up in b/w photos?

(Photo from Taz)
The step also looks to be darker like the holders.

(Photo from Taz)
The horn on the rudder also look dark on several planes but the horn on the elevator, I have seen some variance between the darker color to a match of the green camo. These are on the Dr.I's (V5's) and I will check the FI. (v4's) to see what I can find.
Lloyd...