At about noon, I came down with a headache. It was heatstroke.
Heat exhaustion suggests strenuous activity mixed with heat as a cause, while heatstroke suggests simply overheating (too much exposure to the sun).
I decided to go home. Besides, there was a machine droning noise from less than a kilometre away, like model airplanes or go-carts, for several house. When that finally stopped, all I could hear was traffic noise from the nearby road, a connector road from the highway to in-town.
I went there to maybe meet friendly fellow campers and hang out and maybe suggest a hike or cycle somewhere. People kept to themselves.
I got back at about 5pm, unpacked and put away everything, and lied down with lots of water. Thus the end of my weekend get-away.