In reply to tim123487: There have been a lot of problems recently. carparks turning into tent cities and people generally leaving their stuff strewn around (including hanging in the trees) after camping whilst going out climbing. This both hogs the carparking during the day which is not showing much respect for other people, and quite a lot of the time there was rubbish around these areas.
You could be good though and not camp in the forest but instead use one of the FREE bivy spots.
There is one north of Milly, one at the Hypodrome and one at the northern end of Bourron-Marlotte.
Whatever you do PLEASE PLEASE PLEASE can you take your rubbish away with you.