Oh no, don't do that. Flapperons on a trainer won't do much to get you ready for a scale plane that uses flaps, so that's not much of a reason to do this mod. The good reason is so you can mount your servos out at the middle of the control surface and eliminate all the flex that the torque rod arrangement gives you. You're probably right that cutting an extra servo hole in the middle of your wing probably will weaken it. My advice would be to just fly the thing like it was designed and let that be in. If you want to play with flaps, get an Ugly Stick or similar plane that has them and learn that way.