Visual Contact Flight
In the offshore world - presumably the same rules apply to other civvy operators - one can fly with a minimum 5k vis and 1200' cloudbase at 1000' at night, known as Visual Contact Flight, outside controlled airspace, onshore.
Very confusing issue - but PPLers are doing it all the time...
This is only an en-route ruling though - so can't help with the unlicensed sites bit.