If the control surface is made such that you can recess and glue in a couple of small pieces of thin aircraft plywood, you can just use wood screws to hold the horns on. This method would generally require the surface to be sheeted foam, but build up if reinforced properly would be fine with this method too. 1/8" thick ply sized about 1.5"x0.5" is enough to distribute the load for a 1/4 scale aerobatic plane with a 180 class motor.