Hi
You didn't say if you had a computer radio, and I don't knnow if your plane has a single or multiple servos for the ailerons. If single servo you can't use flaperons at all. If you have a computer radio and a three position switch available, then set your flaps for no more than 15 degrees for the approach, and that will slow down the airplane. No more than that though because you are limiting your aileron travel with flaperons. "After touchdown", and only after touchdown set your flaperons to max to create all the drag possible. Or you can even raise them to create spoilers.