One lasting memory of my XC trip was going against a ridiculous headwind all day for 150 miles. We did that with the help of peloton and pace-line biking. This is the first time in my life that I did that. We had to learn fast how to do that. It is not that simple. The leader in the pace-line lasted for 1-2 miles and you know the peloton rotates leaders constantly.
I still think of that. It was so exiting (and stressful).
Your comment about OHB XC trip brought back this memory. I think that he will have his challenges on that long trip.