It occurred to me that this plane would have shot right up in altitude if it were a kite. The only trick would be if it would fly off the ring at the top. I will experiment with the hook position.
I used to fly kites a lot. If the bridle attachment is too high the kite will go up but stall as the angle changes. Basically it approaches an angle closer to parallel with the ground. If the bridle attachment is too far down the lift is bad and the kite waggles but wont gain altitude.
So to launch a sail plane as a kite it would need to be attached midway between nose and CG. Hopefully it will lose enough lift at the apex that the line will blow off.
If this works it will make gliding on the small field flatland a lot easier.