If they are just strip ailerons and only 17" long and 1" deep already cutting them in half to add flaps isn't going to add that effective of a flap to begin with. If it were me and I wanted to add flaps I'd just use 2 servos and mix them as flaperons. If you want to keep the torque rod set up just run 2 servos side by side in the wing center. 1 on each torque rod and as I said mix them to operate as flaperons. I've had a few jets including my old bvm viper that use flaperons. You won't lose any effectiveness on your ailerons in flight that way.