How good is the ground visibility by a moonless night In the Grand Canyon?
No, in a remote area on a moonless night, it’s a black hole.  It’s the blackest darkness you can imagine with a few pinpricks of light from remote settlements on the ground or vehicles.  I have heard a few stories from pilots flying at higher altitudes on moonless nights, such as Maj Brian Shul who did this over the Arctic Ocean in an SR-71, where they shut down cockpit lighting and found that starlight was intense enough to illuminate their instruments.  I also know of tales from Navy pilots who have flown fighters in dark night over water who can’t see anything out in front of them.  

These conditions require total reliance on instruments to know which way is up and plenty of people have become spatially disoriented flying like this and crashed.  I have heard some hairraising tales from drug runners like Barry Seal, Carlos Lehder, etc., who used to fly airplanes low level over the ocean at night in order to avoid detection, remaining about 50ft or so off the deck.  One guy they interviewed for the MSNBC documentary Cocaine Cowboys used to do this approaching the Keyes south of Miami for a drop off.  He used to say if he could see the light glow of Miami off his nose he was fine but if he could see the glow from both Miami and Tampa, he was too high and risked detection.  God help you if you had a bad altimeter setting in these conditions.

I will make my own comment, as a professional pilot, that dark night conditions over remote areas or open water are downright eerie and there’s is always an uncomfortable feeling in myself when doing PIC operations in these condition.