Are You sure that pattern is not same (that it doesn't continue on) on the fuselage on the first photo You posted?
To me it looks like the light reflection from fuselage just lightened the film more, so it is to light to recognise the pattern (overexposed in that area). I think pattern is going over - I mean there is no firm evidence that something else is on the fuselage.
And the pattern on the drawing itself looks like it is cut in the middle (in a vertical sense) all along fuselage. Are You sure that is the whole pattern?
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We should all try to find more photos of this aircraft if they exist.
Anyhow, this is not an easy job You intend to do.
What is happening, You turned on WWI airplanes for a moment?