Whatever happened to commonsense?
I have flown at many gliding sites - both civilian and Air Cadet training. If any conflict seemed likely, the commonsense rule was to stop moving and face the landing aircraft who could then pick a landing run without having to worry about moving personnel, retrieve tractors, etc. The landing area was situated so as not to interfere with the winch cable run. The winch cable tow-out driver was facing the right way, and his course was obvious - so no need for him to stop except in a rare situation.
Kids, dogs and enthusiasts around the launch point control "caravan" were the biggest hazard, but were always instructed in the safe way to behave. Duty Pilot - who's that pillock out in the undershoot???
And a good safe fun time was to had by all.