Nature reserves/reservoirs carparks are not so good.
I remember during my army days, my team was arrowed to support a brigade exercise as enemy. My deployed location was at kranji reservoir in some bushes, defending the area against naval divers. The bushes are facing the water on one side and a carpark on the other side! We were in full camo and equipped with night-vision equipment.. Best 3 day 2 night exercise I've ever been to....
So no one disturb does not mean you havent been 'contacted'... Be careful! Use curtain or newspaper even if the place seems empty...