Technically there is no end to the number of solutions for this problem, including aformentioned rpm input to the strobe light.
But I belive that most accidents involving propellers araise from a number of factors, but most often fattigue and stress(incl. noise). This is not ment in any way to be pilot bashing, but pilots have working time regulations that not only limits the amount of hours in a day, but also over a given period. A similar solution for ALL ground personell would most likely erradicate most of these incidents and accidents, the only problem being, who would pay for it. But then again, nobody put a price on safety, do they.
Brgds
Doc