Have you tried a super long telephoto lens? If you got like 100 photos in a row you might be able to use some kind of software to blend them and infer the number.
It's only been a couple times a week on random days and times; I'd basically have to camp on my roof to catch them. And they're going full tilt (at least 90 knots) so there's only 5-10 seconds of opportunity. I do have a pretty good long lens on my digital camera, maybe I'll set it up and have it by the door.
