Richard,
Thanks for the reply and your comments. I agree that we can only guess at many such questions; as I like to say about PC10, "Fokker Red", and puzzles such as this one, "the only thing we can be sure of is..................... we're not sure"!
I contacted Richard Alexander at Wingnut Wings with the question and he replied very promptly. The piece of fabric in the photo on page 32 of Kit 32030's (the OAW Built version) Instruction Booklet has a very pronounced brown varnish and he states it is the only evidence he has seen of the brownish overcoat. He also opines that the upper flying surfaces
could easily have been given similar treatment however their Instructions have cautiously(
perhaps too much so) in his words) indicated fuselage only based on interpretation of available photos. Richard kindly indicated to share this information with "other modellers who may be interested".
In the absence of any further info I'll be doing at least one of my D.VII's in your brown tinted Lozenge, probably the RK Scheme, 5324/18 of the Alb version, and using the tinted lozenge on the upper flying surfaces as well. Such little quandaries add tremendous interest to this Hobby in my mind; perhaps as time passes we'll solve some of the mysteries.

It is refreshing that the experts are not exaggerating their cases nor claiming interpretation to be fact; further both you and WNW appear to be in agreement on the answer to this question..............it could be, or not!

Cheers,
Lance