I thought it was a joke at first but faced with 4 K of course marking and hopping out of my car every 100 feet, I gave it more thought and decided to try it.
I could not find chalk that big readily available and so got Wal-Mart sidewalk chalk. The Wal-Mart sidewalk chalk is softer than blackboard chalk which is even smaller. My stick was a piece of bamboo cut just back of a knuckle and split then taped. This allowed jamming in a piece of 1/2" foam pipe insulation. Then the chalk is jammed into the foam. It left a "followable" trace on smooth pavement pretty well. But it broke or flipped out every time it hit a break in the pavement and you were about as well off running ahead with someone else driving or leaning out of the driver's seat and marking with your left hand.
However, with everybody and his brother putting on a race causing prohibitions on paint, somebody needs to engineer something like this you can do it from a car as I don't see a lot of race directors or race timers taking a bike to a race.