I recently pitted for someone who uses just one box for truggy and buggy, and he just eyeballs the position. Only problem was that I never even saw how he did it before the race. Half way through the race he flamed out, and believe me, when you're frantically trying to get a car started it's REALLY difficult when there's no guides to line the car up.
It even took the guy who's car it was a couple of attempts to line it up properly.