I think LE is dead on in their accessment of the height being 5,2" to 5,7". 5in could litteraly be the differance between the perp barefooted with no helment and the thickness of the heels of the boots and the height at witch the helmet rest above the suspects head.
Their 5" gap is what makes me curious about their numbers. That is a big range for the technology they have coupled with access to the exact space with the cameras still mounted in their same positions. They know exactly how tall SP is in the costume. You wouldn't look at barefoot, because SP isn't. The range should only account for the the lowest possible boot heel height to highest, and possible thinnest helmet to thickest. You can't have much of a heel insert inside those boots. Anything much over 1/2" will make it very hard to walk and flex the foot (not cause turn out). An outer lift would be visible. If a thin, narrow boot heel accounts for 1/2", then with a lift + thicker boot heel, you are maybe at 2". I wouldn't put helmet variance at much over 1" either. I am not sure why they need to give a window of nearly half a foot. Seems a bit large to me.