Theory and practice state that a symmetrical airfoil, pivoted at 25% mac has no pitching moment.
In the wind tunnel such a profile can be placed at any angle below the stall, and it won't move with airflow.
The torque therefore is zero.
As a true symmetrical shape can be difficult to construct, and the pivot point difficult to position precisely AT 25% mac, fudging a little forward won't hurt anything.
The torque required goes up though.
Probably not much.
But aft of 25%, the profile as stated will attempt to find a stable angle other than streamlined; this might be full up or full down, or all points in between..
I've seen an otherwise well-designed plane with such a flying tail crash due to the loss of control created by the oscillation (not flutter) of the horizontal around the pivot from stop to stop because the pivot was aft of 25%! Don't do that! .
I put the pivot a bit ahead of 25% on my airplanes with flying tails, both horizontal and vertical.
Haven't lost a servo yet.
I have had a conventional rudder strip gears in an HS-81 though, in flight.
Some equipment is truly made down to a price.
For your purpose, most small servos should be OK. My GP Yardstick uses the Hitec Feather servos, which don't complain about the large surfaces they have to move.