free from all around obstructions;
If the area is free of all obstructions-why would you want to land downwind?
There is a simple rule regarding helicopter operations:
You can do (almost) ANYTHING-as long as you fully UNDERSTAND what you´re doing there...
Your question cannot be answered, as many factors are missing...
Weather conditions, PA, Weight of the aircraft (fuel on board, pax,cargo), dimensions and structure of the landing area and the surroundings and much more...