Interesting to read this "old" topic on measuring cross-country courses. I occasionally get an inquiry about measuring an off-road course for certification. I always say that I can measure the course accurately, but USATF will not certify it. As pointed out here, the best reason for this is the obvious difficulty in re-creating the route in the way it was measured. And this assumes the terrain would support a good ride.
However, GPS devices are practically ubiquitous these days. I sometimes am challenged by Garmin-wearing runners about the differences in measurement they get on this or that course from my certification measurements. I usually dispense these discussions (with good nature) by asserting that only Lidar will give them truly accurate distance readings on anything but a perfectly flat, open course. "$50,000 and a giant backpack and you are in business" I tell them.
But GPS readings can pinpoint a course within certification tolerances. I can image it wold be a pain to measure or to lay out a course checking GPS readings every few yards. I am just saying it can be done. When would it be worth it? I have no idea. Probably never.
I'm just sayin'...
Lyman Jordan