I did 49 winch/autotow (mainly winch) in the old 'Blanket' - both in africa and britain.
From the L13 Pilots Notes
WINCH LAUNCHING
If original towing-bridle is used, the maximum weak link strength is 2,000 1b. (910 kp).
For maximum launch height, the side-towing bridle should be used. To reduce the possibility of
"whipping", the towing-bridle should be laid out in front of the sail- plane before launching. During take
off, as the control loads are very light, care should be taken not to climb too steeply at a low airspeed, and it
is important when releasing the cable to pull the release handle fully so as to allow the cable hooks to fall
off.
The nose hook, which embodies a back release mechanism, also may be used for winch launching.
Partial flap may be used during winch launching, if desired, in order to reduce the take-off run. A speed of
54 knots (100 km/hr.) should not be exceeded if the flaps are extended, or 65 knots (120 km/hr.) with the
flaps retracted.
The recommended speed for winch launching is 43-54 knots (80-100 km/hr.).
I must add though that I always used the side(belly) hook and never tried the nose hook for winch launch !