I use
letter stamps, and stamp the event initials across the top, and the split identifier across the bottom of my washers.
Yes, it is time-consuming, but it helps to identify the location, especially where there are multiple courses in a park. I don't do it for every course, but I should. Sometimes I just don't have time to do it between notification of a course to measure, and the measurement. Of course, I only do it where I am measuring in asphalt.
Also, it takes a Number set, in addition to the Letter set.