You can mount the servo on its side but 'up side' down (pic 1)
and use sullivan high stress rod (pic 2)
http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXFV12
to move the moving surface internally.
Just Glue the outside black tube into the moving surface as you would a robart pin hinge.
Then attach a ball link to the servo arm and then attach the yellow internal rod to the ball link with some 4/40 threaded rod.
As the servo arm rotates up/down, the moving surface moves in the opposite direction.
The yellow rod slides in the black tube.
It's like drilling a hole in the side of your house door nearest the hinges and then sticking a metal rod into the hole.
As you move it left or right, the rod will slide in the hole but also move the door in the opposite direction.
Clean and simple and very scale.

I stole this from Gary Webb when I bought one of his planes.