The ONLY place to mount your propulsion is off the rear, the response and crispness is immediate. When engaging reverse you have instant control, unlike mid mounted drives, which are like trying to turn 180 degree with the Mirage drive from a dead stop,You have to give a few pumps and retract the fins and crank the rudder, it takes too long and is inefficient.
With the drive in the rear of the boat, you'll be able to spin 180 within your own length.
Another problem is clearance, with the motor in the Mirage Drive slot you have to watch out running aground, without the ability to raise the motor quickly is asking for trouble. You would treat the motor the same way as you would a Mirage drive unit. Removing it as you come ashore, where as the rear mounted motor could be raised at will.
And the biggest disadvantage is that you won't be able to use both the motor and the drive at the same time.
I use the Mirage drive to get where I'm going or to get my exercise or yes, to save battery, I use the motor to fish, fishing with the Mirage Drive isn't ideal ( it's better than a paddle, but not than a motor).
Another advantage of the rear mount is that it is Hands free, one of the benefits of the rear mount motor is that your getting your hand off the rudder allowing more important functions.