Turning the servo on it's side is without doubt the best place but nothing repeat nothing will cure your (and everyone elses) problem unless the lenth of the horn (from the control surface center, ie hinge point to the clevis hole) is exactly the same lenth as the servo arm (from the center screw to the clevis hole).

These dimentions can be as short or as long as you like it... simple dosn't matter as long as they are both the same length! The concept of placing the clevis futher out on the servo arm to increase throw dosn't work with pull-pull.
There is only one throw, max inboth directions and this must and can only be achieved successfully with equal servo arms and control horns.
All increases and reduction of throw are controlled from the ATV function or similar on the transmitter.

This will cure your problem.
Enjoy the aeroplane.