Nope. Sigh.

That would certainly help, though.

So you didn't like the idea of the Earthlit lunar limb against stars? Hmm - asteroids within the main belt often have apparent motions fast enough to tie down times to a few seconds easily. I have found, though, that you need to grab the latest JPL Horizons ephemerides - even a week ahead of a pretty close approach can put the prediction arcminutes off if it's new to us and still having its orbit refined. If you could do simultaneously observations from elsewhere, that would tie down the position independently along the axis parallel to the projected separation of sites (and if you could arrange for that to be perpendicular to the relative motion, that leaves only the timing to solve for). We've done that as an exercise between the campus telescope and Kitt Peak, which is when I was impressed with how simultaneous the images need to be to show only a parallax shift.

Well, whatever method you use SM, good luck!

And here's hoping that you'll let us all know, in the end, what worked (and, perhaps, what didn't), and whether there was, indeed, a ~10 second lag ...