I would STRONGLY recommend ailerons on a tug.

I would also recommend using a larger plane for more dominance over the glider.

Also, it is best to attach the pull string to the top of the wing at the CG. Attaching it to the tail can be disastrous because if the glider rises above the plane (Which they are notorious for doing since they have so much lift) it will pull the tail up - which will force the tug down - which will result in more speed - which will result in the glider producing more lift - etc

With the tow line at the CG, if the glider rises above the plane, it will just lift the tug at the CG