Can you put a request in for the road to be re-swept beforehand? And tell them that the contractor is NOT to leave gravel piled up at corners and intersections?

NZ is pretty much all chip seal roads. In events we give out brooms to the marshals on the corners to clear the loose gravel off the road. However to be honest riding different road surfaces is all part of the "fun" of an event. Imagine riding the cobbled roads in France!