In an elevator setup which has large throws - ANY offset is easily seen
A really easy fix is to make a fork- identical in distance from center when measured side to side .
Then, put the center of the arc on c/l of the fuselage.
If possible - put servo on it's side - then there is theoretically (Love those theories), no parallex.
Another easy fix is to tilt the servo to 45 degrees -
This will negate a lot of the side to side swing and you can still easily reach the mounting screws.
My elevators typically deflect up to 45 degrees each way -so any goofup is very easy to see.