With torque rods... you could have the aileron servos in the center of the wing, side by side. This would eliminate the drag of external control linkages. (which is minor...)

Typically, the servos would be appx 1/3 to 1/2 of the control surface's area out from the root. That would be in the 2nd 3rd bay out from where the wing meets the fuselage. You really can't place the servos badly if you try to almost center them on the control surface.