I would believe the actual focus over anything on the distance scale. Focusing on the moon should have been a good infinity target. The distance scale doesn't show the DOF like older lenses that had DOF markings for most apertures. I would focus on something at approximately 15 ft in manual. The DOF calculator will work for any Nikon DX format camera.
I guess I'm not understanding what you're getting at. With an 8mm lens at f/3.5, the hyperfocal distance is 2.97 (basically 3 ft). If you set the focus to 3 ft on the lens' distance scale (if it was accurate) or focused on something three feet away, everything from 1.5 ft (half the hyper focal distance of 3) to infinity will be "in focus". The definition of hyperfocal distance is the distance at which every thing from 1/2 that distance to infinity is "in focus". Only the distance focused on (3 ft) is actually is true focus, the rest is in acceptable focus. Maybe you knew all this.
>It looks like there is not much interest in this subject.
Your issue is quite specialized and not specifically a D7000 / D7100 issue. I think that you will find much more interest and advice in the "Astrophotography" Forum, in the "MASTER YOUR VISION -- BY SPECIALTY" Group of Forums. Try re-posting there.
I knew that you planned to make a post on the subject but didn't know which forum you'd use, so I looked at your nikonians profile, its Posts Tab, and saw this listed as a recent post. I then just clicked on the link.