Your message is several years old and you may have found all you need. However, I know something of John Ferguson and would be interested in hearing from you.
I am researching Australians and New Zealanders who took part in the Klondike Gold Rush and, while JF is just outside my target years, I have come across him in my research in the Dawson City Museum. By now, you very likely have more info on him than I have in my files.
I suspect he may be the ragged man who spent his days reading in the library in Dawson City Library, as recounted by Laura Berton in her memoirs (I married the Klondike) . No real evidence, just a hunch.
Dr Robin McLachlan
Charles Sturt University
Bathurst, Australia 2795