meself, I think you are right that Stan "made up" the name Kelso: I found this online "Stan Rogers discussed the process of writing Northwest Passage in a radio interview in 1982 and admitted that he had been unsure of Kelsey's name and had guessed Kelso while recording the song." (http://http://www.sea-of-flowers.ca/weblog/sea/archives/2004/04/brave_kelso.php)

Let me just add that I love both Stan's song and Lady Franklin's Lament, and often do both.