As one of the "various decal manufacturers" who "copied" these markings from the Windsock Jasta 5 specials, I'd like to add a few comments, if I may.
If you have the two Datafile specials, the photograph on page 7 of volume 2 is the only one I know of of this aircraft. If you compare the grey tones of the red (known) tail outline with the unknown colour of the fuselage then red would be a good choice - likewise the spinner grey tone compares well with the (known) green tail, thus green is a good match for that item. At the time (February or March 1918) that this photo was taken, the red nose band, directly behind the prop spinner, was still worn by other Jasta 5 aircraft but many of the later Albatros D.Va arrivals don't seem to carry this marking, so its apparent absence from Gürke's machine doesn't help with defining the fuselage colour. All we can say with
certainty is that the spinner and fuselage were different colours. We don't seem to have the serial number of Gürke's D.Va, so cannot say when it was likely to have been received at Jasta 5 anyway - although it is certainly a D.Va (note the aileron actuator gap in the upper wing and cables running up to it). It should be noted that the photo is markedly under-exposed, which makes interpretation even more tricky.
If I was looking for reasons to paint the fuselage black, the one straw I would grasp at is that the red spinner is a very common marking for Jasta 5 Albatri (although by no means universal) and green seems not to be and most other photos show the (apparently) red spinner as an unexpectedly and consistently light tone for red. I hesitate to suggest that all the spinners thought up to now to have been red were actually green.....
As far as I know, there is as yet no new documentary information identifying the fuselage as black. It is likely a simple re-interpretation of the photo. Looking at it again today, I can see nothing that would make me say that it was one or the other. I went with Dr.Merrill's interpretation (I don't think he had any documentary supporting evidence, so I
assume it is simply interpretation) because it was the best I had at the time.
I know that researcher and author Bruno Schmäling (co-author of the recent superb Jasta 30 book from Aeronaut) is hoping to produce a new volume on Jasta 5 in the future and he promises some new revelations therein, so perhaps we will know more then.
So, if you want to build your model now, you could make a case for it having a black fuselage and also a red spinner, should you so wish, or you could wait until the new book appears to see if there is anything new - a bit of a long shot.
Here's a revised profile - note also that the struts and wheel discs should be the same colour as the fuselage - either red or black. Something I missed from my earlier profiles with the decals, and will now change that aspect for future distribution of sets
32017 and
48012.