Ask any full size glider pilot about this and the answer you will get is to keep the yaw string centered. In a tight thermal turn that almost always requires "in" rudder and "top" aileron. I'm no aeronautical engineer (or any kind of engineer for that matter) but I do know that a coordinated turn is the minimum drag turn. Wing drag and fuse drag are not terms I've ever heard.
Fly a full size and watch the vario while playing with the yaw string. As soon as that string gets a little off center the vario shows you going down. The farther it gets off center the faster you are going to come down.
Maybe our toy airplanes fly differently, after all, the models seem to know when they are in a downwind turn