1/16" is really nothing to worry about. You'll be fine. One suggestion I'd make to try and reduce this further is to maximize your control linkage resolution.

Use the smallest servo arm, coupled with the longest control horn you can use to get the required throw with your ATV's set as high as possible. This lets you use all 1024 steps of resolution of the radio and minimizes the effects of gear train slop at the control surface.

One comment.. I would NOT suggest using the 8411SA on something like this. Where a normal analog servo with nylon gears would blow back if over stressed, the motor in the 8411SA is strong enough to actually break the gears in the servo if too much force is applied. Stick with the standard 8411.

Doug Cronkhite
Team JR