Really, you'll have to show what regulation supports that.
Nope. Other way around -- unless you can show approval of the airport for YOUR flight operations, it's no different than the surrounding land. If you're in a KingAir, that 800' ultralight strip isn't an airport.
Here in the Western deserts, there are a LOT of places that one can land and take off -- highways, roads, dry lakebeds, bare desert, ultralight fields, model airplane strips, abandoned WWII training fields, etc. Just because something LOOKS like an airstrip doesn't make it suitable for landing, which more than one pilot has discovered. In fact, most private airstrips are unusable, and are on the charts simply because nobody has said to take them off. One near me was graded back in 1941 and hasn't had a plane (or maintenance) on it in years. It's still on the charts, because the owner likes to be able to tell people that he has his own private airstrip.
Yet another strip, graded by the Navy for pilot WWII training, isn't even marked as an abandoned field on charts or topo maps. You can see the strip for miles, but according to the FAA it's just another patch of desert.
OTOH, another poorly-maintained strip nearby is for sale, and the owner has ASKED us to use his field, to show continuing use by aircraft. A couple of us will periodically shoot approaches (none of us dares land on it, even the LSA guys).
Even if you land at a private airport without permission it's not going to be a regulation bust.
Are you sure? A private airfield is controlled by the owner (according to the FAA, who approved it as a private airport in the first place) who either has or has not given you clearance to land there. Landing at a controlled airport without clearance IS a reg bust. And taking off just might not happen (nothing keeps the owner from parking his car on the runway and making you trailer your plane out, AFTER you pay whatever he decides to charge as a landing fee).
But especially with respect to what we're talking about. If you don't intend to land you can not fly closer than 500' to a person, vessel, or structure. It makes no difference if it's ORD or NC26. There have been enforcement actions that the pilot lost on appeal. If you make a low pass you'd better not violate the minimum altitude rules nor do anything else the FAA may throw a 91.13 at you with.
Yep. And you have to be able to SHOW that you didn't blow the 500' rule. About the only place to be able to do that is the middle of a dry lakebed, AND if you're shooting video that shows it to be absolutely empty.
Otherwise, it just takes one annoyed person to say "I was walking out there and this plane came whizzing right over my head!"
There aren't many private airports which don't have a building on them, so shooting your approach, even if you abort, is likely to take you within that 500' . . .and you can pretty much assume that anyone with a private field is also likely to report unapproved low passes.