Since my one way travel distance to Ely is 1200 miles, I opted for removable; but I also have "snap clips" ever few inches from the unit mounting position to the transducer ... keeps the transducer wire from getting snagged when loading/unloading gear at portages and campsites.  However, I went the epoxy route for mounting the clips rather than pop rivets.  Quite frankly, I didn't want to add more holes to the side of my craft which might potentially weaken the overall structure.  (That's probably being overly cautious.)

dd