Flapperons are ok for short runways, but full strip flapperons will have a tendancy to put your nose in the dirt unless you simultaneously add enough elevator to compensate. They will also cut your roll rate. The only way you can use flapperons with a 4 channel is to adjust the linkage to the ailerons so that they are both down the same ammount from their center position. What you can do, is install a servo in the wing bay for each aileron, cut the aileron at 1/3 of its length from the fuse, and use the existing torque rods for the flaps. but to do that, you're going to have to remove and rehinge the ailerons. You can do any nomber of things to hold them both in preset positions, and later, when you get a 6 channel radio, all you have to do is add a servo.