we are possessed of an Airhead GSPD, and a K75 Low Seat Standard. Thinking of putting a hack of some sort on one or the other bike. Which one? We prefer adding a chair to the K bike, but what hack and how much is involved in mounting and setting up on the K v. The Airhead? What hack? My only real requirement is an electric lean/trim assembly. I’ve had hacks with and without the magic switch, and it’s almost a must-have. All advice welcome.