You could likely silence it with some hunks of foam to stop the rattling.  Turn up the volume on the radio & sing along?  Just a small town girl, livin' in a lonely world!

Double-blading a canoe isn't going to get you kicked out of the club.  Standards have slippled in recent years.   :D  Depending on the canoe it may not be practical, but any dedicated solo boat should work well.  My fat prospector would need a huge double-blade to keep from knocking gunwales on every stroke.