Hi Mike,
Once again you have posed a question for which there is no easy nor definitive answer. Since you're referencing Naval 9 (and not 209 Sqdn RAF), I presume you must mean that this report comes from 28 May 1917 (and not 1918).
The use of "checkerboard" or quartered markings was quite widespread and such markings are seen on many different fighters, and in many different patterns, etc. The coat of arms of the Hohenzollerns was quartered in black and white, and the Prussian Observer's Badge featured a black/white quartering or checkerboard; this inspired the use of such markings on many different aircraft.
Many years ago, Alex Imrie first stated the the Albatros D.Va 5426/17 seen in this take-off photo of MFJ I at Aertrycke was flown by
Gotthard Sachsenberg.
However, that was a long time after 28 May 1917. The photos of Sachsenberg's D.Va all likely date from the Spring of 1918, such as this one, with Sachsenberg himself under the 'XX' mark.
And as here:
In May of 1917, Sachsenberg would have been flying an Albatros D.III, and I don't know if he used a similar checkerboard marking on any of his D.III's. I've only seen one rare photo of Sachsenberg posing with a D.III, and it seems to have been in a factory finish. Other Naval pilots in MFJ I and later MFJ II also used checkerboard markings.
This D.III in flight is said to be a Marine Feld Jasta aircraft, but that's all I know; I sincerely doubt that it was flown by Sachsenberg.
If I were you, I'd be very cautious about attributing the reported 'single seat scout with a chequered design' to any particular unit or pilot, beyond perhaps a cautious statement that it may have come from MFJ I - based on the location more than anything else.
Best regards,
Greg