I think the original use of the Telemaster was to string lightweight cables across valleys in Germany, I remember reading about that 30 or 40 years ago. Perhaps that is why they decided a lifting tail was of some value.

Kurt has flown full size aircraft with a lifting tail if I remember correctly. Or more correctly, he controlled the computer(s) that controlled the airplane. Four computers that voted to decide what the correct solution was to maintain flight. On a later variant, the tailplane was enlarged to enhance the load the airplane could carry. I think that was the C/D version. It's been such a long time since I've read Aviation Leak.