This is one of the risks you take by flying cliffs in a glider, it is very much an adventure sport and all part of the challenge, it occasionally it goes wrong. The cautious way of starting a turbo is to pick your field first, from a sensible height and anything less than 1000 ft is risky because with a windmilling prop you loose height quickly.
The Duo Discus is probably the easiest starting turbo the engine will start at not much more than 50 knts so you should not loose much height, BUT, if something goes wrong and it doesn't fire up down you go. Quite likely turbos have slipped below the cliffs before and cruised away with the motor, thankfully no injuries, does anyone know the fate of the glider.