Blu Tac, You are quite right my wayfarer is uncontrolable in any conditions where waves are hitting you in rear and the motor is mounted on the extended bracket ( 10” rear of the transom). My first attempt was locking the motor steering swivel and using the rudder, But the lock on my new Mariner will not hold.
For the next attempt I used control lines about 4′ long (as used on model aeroplanes) to regulate engine speed not idea, but not bad. For steering I used 1.25”
plastic pipe which happens to fit perfectly over motor steering handle This also was about 4′ long this did work,but is not the answer.Personally I don’t find any of this satisfactory,The motor is too far back and i am not happy being that far to the rear, Shall try to get prop deeper and clamped directly to transom.