I help set up a half marathon course in a park where we are not allowed to mar the road surface with either paint or nails. To top it off, the split locations have to be found well before sunrise. The nails are planted at the edge of the road (where they are often covered with gravel) and finding them in daylight can be a challenge. I have a record of the splits' locations in relation to landmarks, as well as GPS waypoints recorded to aid in finding them. The afternoon before the race I lay down brightly coloured duct tape on the road and plant a 1 m long stake with a reflector on the side of the road. The reflectors are quite visible in the dark from 30 - 50 m when they're illuminated by a vehicle's headlights.
Some other tricks I use for night measuring. I place flashing LED tail lights and/or traffic cones at the ends of the calibration course in addition to freshening up the paint. I have a 10W halogen lamp attached to my helmet which makes reading notes, calculators and counters a lot easier.