Maybe I can help with the Defoe connection. My partner Rika Ruebsaat collected "Forty Below" at a fairly drunken party in Winnipeg in 1975. She and I were ignorant of the song's provenance and asked around, through our newsletter and the two publications we edited "Come All Ye" (1972-78) and "Canada Folk Bulletin" (1978-1980), and whenever we performed the song. We never heard from anyone. Edith Fowke added the song to the second edition of "Canada's Story in Song" (now called "Singing Our History" (1984), the subtitle of the first edition, 1954)and acknowledged Rika and "Canada Folk Bulletin" as source (p. 240). We used the song in one of our radio shows in the series "Songs and Stories of Canada", aired by the CBC as a schools broadcast in western Canada and included it in the Guide we prepared for the shows in kit form. Holt, Rinehart wanted to use the song in their textbook "Musiccanada 5" and we gave permission. The next we heard was a few years later (in 1988) from Chris Dafoe's lawyers. He had apparently made the song in 1959 and published it in his column in the Winnipeg Free Press. Another song tracked down! I sent the song in to the DT with the updated note on its now discovered author. He himself has written a fine piece titled "Just Another Folk Song" describing the songs travels through the world, via (of all people) Alex Campbell.
Bye the bye, the article of Edith's in which she claims a Canadian/Metis origin of the original version is to be found in "The Red River Valley Re-examined", Western Folklore 23 (1964), 247-256; reprinted in Alberta Historical review, 13 (1965), 20-25.