Dial the epa's up to the max available. Depending on the brand that could be 125%, 140%, or 150%. Then, using linkage positions on the servo arm and the surface, obtain the maximum travel desired at the highest rate. That will likely be at a little less that the amount of servo travel available. That's good because you won't be as quick to over drive the servo and damage the gears.

Maintain mechanical advantage to the servo and don't go overboard with the distance out from the servo output shaft. You probably won't need to go farher than 1", but 1-1/8" is also pretty common. The surface side of the linkage should be farther out from the hinge line center than the distance out from the servo output shaft. Never less. Then dial the low rates if ising dual rates.

Unless you're very good and use a tremendous amount of expo (not a bad thing by itself), you may discover the plane is quite a handful on a single rate. Dual rates is a good thing. "Conditions" and/or triple rates is even better.