Unfortunatly you've just stumbled onto one of the biggest problems with the Frank Mayer story. There is no record of Frank Mayer outside of "The Buffalo Harvest" and some 1930's vintage articles written by him for "The American Rifleman" magazine. It's as if he just crawled out of the woodwork at 80-something years old. If there is more background information out there I'd sure like to see it.
If you read other books on the buffalo hunting era you'll find some cross-referencing. For example Jim White was mentioned in several books and stories written by others. John Cook (The Border and The Buffalo,) O.P. Hanna, (I believe) Billy Dixon, Collinson and others knew - and wrote of - Jim White. But Frank Mayer is not mentioned by any of his contemporaries. This is strange as he, being one of the more successful of his kind, would have been well known.
As for Billy Dixon, his experince at buffalo hunting was somewhat brief. He gave up that line of work after the Adobe Walls battle in June, 1874. That was the peak of the buffalo hunting era in Texas or maybe a bit before the peak. A few hunters, Jim White among them, started at the beginning (about 1871-2) in Texas & Kansas and stuck with the hide business until the bitter end in (1882-3) Montana. Well, almost - Jim was murdered in October 1880.