I learned the tune in 1970 or '71 from a 2-volume "complete" Jimmie Rodgers songbook, with the same key-of-F chords cited above. The B-flat to B-flat-minor change always sounded right to me.

I found it difficult to play, at first, because I used to avoid barre chords (using my thumb instead), and this song in this key pretty much requires the use of at least some barre-chord fingerings to make the changes quickly enough. Considered transposing, but *something* was difficult in every key I tried, and I wound up learning to do it well enough in F. (As it turned out, this was the best key for me to yodel in.)