If you really want an accurate assessment, don't go to a range. Do it on private property, or BLM/public land. Don't use paper, use steel, a 12" plate.
Unknown distance, 300 - 700+ yards, no wind flags, no flat range, uphill/downhill, one shot, 45 seconds. You either hit, or you don't.
If you really wanted to make it more challenging, you wouldn't point out the target, you would just take the shooter to the firing position and start the time.
Other shooters would have to be out of view of the firing position, and shooters could not mingle after the shot was fired, no helping your buddies.
Repeat as many times as possible, with the last stage being a tiebreaker. Put the "tied" shooters on the line together. Time starts, first hit wins.