Can't help you on yer expose at all, but last month I went to the "Planes of Fame Museum" in Ontario, California, and managed to stitch together this in one of their 4 very crowded hangars.
My search goes on.. but for many reasons l doubt a resolution.
l have trawled, in amateurish fashion, across the SW Pacific records of September 1942.
The period was a tipping point across the globe.
The linked page is the closest l will probably get to the US pilots fate,
At the time the Bell was being evaluated, the AAF was deep into "streamlining" as a way to improve aircraft performance. This is somewhat understandable, due to the relatively low powered aircraft engines of the 1930's. By reducing drag, especially parasite drag, the engineering minds at Wright Field found that significant increases in performance could be attained. This was all well and good. Unfortunately, they carried it too far as it related to the XP-39. NACA engineers decided that the Bell's turbosupercharger inlet created too much drag. Certainly the inlet generated no greater drag than did the Prestone inlets on the Lockheed XP-38. Nonetheless, they were insistent, the inlet scoop had to go. They reduced the height of the canopy, chopped 2 feet off the wing span and lengthened the fuselage by over a foot. A less powerful Allison with only a single stage mechanical supercharger replaced the turbosupercharged engine. This effectively eliminated decent high altitude performance. Thanks to these changes, the Airacobra had it's center of gravity shifted further aft, exacerbating its already marginal stability. All said and done, the people at Wright Field had reversed the old cliche, and created a sow's ear out of a silk purse..........................