I usually do not include splits on the map unless they help me define the course. Without a detailed location of the split I don't think they add any value especially since the certification does not include splits. My maps are cluttered enough with all the data needed to clearly define the route.
I prefer to keep the map focussed on the course and give the race director adequate information in a separate package so he/she can accurately locate all splits. I used to use a photo file with distances from physical structures, like power poles, marked on the pictures. Now I record a split waypoint using my GPS when I measure, adjust that using Google Earth, if needed, and give a GPS file to the race director. This saves me a huge amount of time and allows the split to be quickly located using a hand held GPS to within a few metres. It also means no paint marks on the road and the crew putting out the signs find it much easier and quicker than looking for paint marks or reading a split manual.