Easy, just get a side bracket made from alumium. If you go electric power you don't need a large motor. I've used the old Mariner T21 on the back of 14ft canoes and the main thing is that the longer shafts on the larger motors and the extra weight on the side can be a pain. I haven't tried petrol power at all on them. Also you will find that the side access to the motor easier to use.