"Hi Stephen,
I've attached a patch view from one of my 1:20 scale drawings of the first series D.III. As you can see, you're correct about the cowling openings. There are three 40 x 400 mm slots in the bottom center - they're continuous, but appear to be divided because of the bearing spider underneath. Flanking these openings are two 180 mm circular holes, which, in addition to cooling the engine, provided mechanics with access to spark plugs and the valve rocker arms. They also allowed the mechanics to squirt thinned benzine into the cylinders, part of the standard startup procedure. The perimeters of these openings were edged with 10 mm wide reinforcing doublers.

Regarding the lozenge camouflage, I hesitate to disagree with so redoubtable an expert as Dan-San Abbott, but here goes anyway: I think you're right. The generation of the copy photo, as well as its exposure and darkroom practice, will have a strong influence on its saturation, so I'd consider its appearance as inconclusive. I'm more inclined to assume logical behavior on behalf of SSW. Idflieg stipulated dark lozenge fabric on the upper surfaces and rudder. SSW should have had ample stocks of the dark fabric, so why would they go counter to Idflieg's directive?

There was mention of how the lozenge pattern seemed to be different on the ailerons. On the first series D.IIIs, the fabric was laid onto the upper wing at a 45° angle. In a top view, with the nose at 12 o'clock, the seams run from 10:30 to 4:30, and the run of the pattern reverses between adjacent panels. On the lower wings, elevator and all ailerons, the pattern runs spanwise. Most likely, underside patterns mirrored the upper surfaces, but we don't have any photos to confirm it.

Please feel free to use the sketch and any or all of my comments.

If you have any additional questions, please let me know.
Best regards,
Dick"

Thank you for the details.
I have opened my CMR 1:72 Schuckert to compare cowl to sketch
only to find both early and late are missing!
I will scratch build a cowl