Carefully match drilled the Z section servo support components to the trim cover plate, dimpled the plate and supports and riveted together with flat head 3/32" rivets.
The servo itself sits at an angle, and the aft-most pair of rivets when set properly sit a little too proud for the servo itself to fit. Not to worry - a check of the Internet to see what everybody else does, and I follow the crowd; that is, set them correctly and then file the shop heads down to allow the servo to fit.