RE: set up for obtaining more control surface travel
The servos are designed to be over traveled electronically, you cannot over drive a servo by changing the programming in the Tx. By doing it electronically you aren't changing the leverage and thus force requirements of the servo. Which wont be a problem unless your servos are so under rated that a small change in mechanical advantage will stall them. But to change the throws mechanically here is what to do..
At the servo; more control surface deflection = farther out on the horn.
At the control surface; more control surface deflection = closer in on the horn.