Clint
While the Camel as you say was used by Clerget for various engine tests the Nieuport monoplane fighter prototype is more shady.
Late in the war (well from mid 1917 or so), the company tried its best to renew their designs and even drop the biplane formula and try the monoplane shape.
There are various photos of one (or two) airplanes built from late 1917 to early/mid 1918. They all conform to the same monoplane shape with mostly different landing gear and tail configurations. For all I can say, it could actually be one and the same airframe rebuilt over and over again.
They (it?) never received any type number which to me indicate that maybe Nieuport itself was not very interested in switching to monoplanes. Since they continued with their biplane designs and was given large orders for their Nieuport-Delage 29 model, I would say were quite correct!
Checking my sources, they are very reluctant to give anything away, and most seems to repeat what Jean Noel stated som 50 years ago....first aircraft being under construction in October 1917 and the idea being abandoned in May 1918. They all show two-three photos, this one being one of them.
Cheers
Stig