That would be my guess too, especially way out from any large airports.
They used to fly low-level training missions out of Rosecrans Field in St. Joe, MO. It appeared as though they were using our house as a landmark. I was running the planter one day, cap pulled down, headphones on, ROPS canopy overhead, D360 talking through a straight pipe, watching what I was doing, when a great big shadow went right over me.
I looked up and there was a big ol' C130 going right over me. Don't know his altitude but I'd guess well under 500 feet. Gave me quite a start.