I believe part of the interest in the upcoming USAF Museum visit is to review as many of the types that visited Canton as possible for this very reason - we're not overlooking the possibility of a 'mother ship' for 2-2-V-1 among those types.
The B-17 construction methods you pointed out earlier are appreciated as well, for sure...
No mistake - these other possibilities have to be reviewed. But 2-2-V-1 remains an enigmatic and telling artifact - it is complex in its own way. Yes - there are discrepancies between the rivet patterns and the known Lockheed original design, but not beyond reach considering alterations and repairs that NR16020 easily may have had given her known history. To turn away from what this part is telling us so far means to find a better match elsewhere, or more compelling information about how repairs were being done on nearby Canton, etc.
This official history, written in the 1950's I believe, makes it clear Canton Island was extremely important as a repair station/depot during the war.
['Canton' turns up 25 times in the text.]
http://www.ibiblio.org/hyperwar/AAF/IV/AAF-IV-9.html
"Army Air Forces in World War II- Vol. IV the Pacific: Guadalcanal to Saipan; August 1942 to July 1944"
Chapter 9: The Gilberts and Marshalls
"...The field at Baker, built by the 804th Engineer Aviation Battalion of the Seventh Air Force, had one 5,500-foot runway covered with steel mat, together with hardstands and parking mat to accommodate twenty-five fighters and twenty-four heavy bombers... In planning to base air units on these outlying islands, as much in some instances as 2,000 miles from the Hawaiian Air Depot, the Seventh Air Force faced difficult problems of service and maintenance. The individual bomber and fighter squadrons could supply first and second echelon maintenance within their organization, for the ground crews would accompany the flight echelons, but they hardly could be expected to perform third and minor fourth echelon service. In the forward area, anything approaching standard service facilities could be expected only at Canton, where the 422d Sub-Depot and a detachment of the 17th Base Headquarters and Air Base Squadron were located after July 1943.
Page 294
Mark, I read the article with particular attention to the references to Canton, and other than the rather general statement you cited above didn't find anything that set me on fire about Canton being a heavy maintenance depot. What I get from all this was that Canton was better off than most other outposts - grant you that.
Nonetheless, in addition to the types we already knew of, it appears to me that we ought to add the P-40 and A-24 ("SBD Dauntless" in fact) for review as potential hosts to 2-2-V-1. Those were mentioned as transiting / guarding from Canton at one time or another.
That's not to demean the excellent research in your finding and sharing these things - just that we have to focus on the meaningful details and not just point to the general condition of a fairly busy but remote island / airfield.
A fitment problem and other hosts being possible is realized; however, just as critical, a fitment to an alternate type must be shown reasonable or Cinderella should get her shoe back after the dance.