I did watch a live demo of a high-performance jet sustainer glider using an auto tow on a short rope (IIRC, a conventional aerotow rope) to get the sailplane moving fast enough to spin up the jet and get off the ground, at which point (less than 100 feet) the pilot released and climbed away, with plenty of room to land straight ahead on the [hard surface] runway if necessary. Pretty impressive. But no interference with an FES prop to worry about.

I also watched an FES ASW 27 self launch a few years ago from a hard surface runway. Also pretty impressive.

Chip Bearden
JB