At the time the song "Boots" was written, Dylan was working at lighting speed, and it is unlikely that he was consciously considering the meanings of any of the words or concepts his songs contained. He had been reading both prose and poetry very widely and listening to lots of different sorts of music. The influences, tunes etc that surface in the songs from this time reflect the mish-mash of creativity that marks the true wordsmith. Using words like "structured", "constructed", "deliberately borrowed" in this context is meaningless. In the folk scene of the sixties, everyone was using, borrowing, reshaping other people's work and drawing deeply on the old folk traditions. I have been singing this song for 40-plus years now and personally doubt whether "Spanish Leather" has any real meaning, outside of the fact that it gives a different, puzzling and charismatic quality to the ending of a song which seems to have been inspired by (though there are no direct references to), his break-up with girlfriend Suzie Rotolo. You can analyse Dylan and his works to death, but the joker-man will always elude you....