Doc - I don't know who any of them are, but Larry Whiffen Sr. is certainly a very good place to start our investigation...
Larry Whiffen Sr. and Fred Bear was close friends and strong business associates until the untimely death of Larry Sr. in 1960. They each sold products manufactured by the other and over the years each featured the other parties products in their company's catalogs. There are several photographs of Fred and Larry together.
In the famous 1938 Colorized Photograph taken at the Continental Divide at MacDonald Pass, where Fred and Larry Sr. are both at full draw and Fred is shooting left into one drainage and Larry Sr. is shooting right into the opposite drainage, Larry Sr. is anchoring under his chin. Fred is shooting a static tip Grumley, and Larry Sr. is shooing a longbow.
The MacDonald Pass Photograph was taken in August 1938, which likely would have been within a year or two of when the photograph of the 4 Bowmen was taken. Larry Sr. was a slender man in 1938, he has a round face and receding hairline. Being born the year before Fred Bear, Larry Sr. was 37 in 1938. I've known both of Larry Sr.'s sons for over 30 years. The youngest, Grant, at age 37 was a spitting image his father's 1938 photograph.
Judging from the MacDonald Pass photograph, I would have to say that, at full draw, the bowman at the right looks very similar to Larry Sr. at full draw in the 1938 MacDonald Pass photograph.
Doc - Thanks for your great input. Now need to follow up with this possibility and do a little investigative work...