Capping the transom between the motor well sides might be a good place. That would just about eliminate what little flex there might be across the transom since the rectangle that the motor bolts to would then be braced on three sides with the motor well and the top would have an inverted U shaped CF beam across it. Probably not absolutely necessary, but still not a bad place to add a little overkill for promotional purposes.
They are the "kings" of pop-up hardware.
