Visited recently this camping site (but decided not to camp as even 800m altitude was not enough to get the cool temperature)
How to get there - you should follow to the Jabel Jais area, and already from the Jabel Jais secondary road just get the turn right to the offroad track. The first few kilometers are relatively flat, crossing few wadis, but when the road goes up it became really difficult: steep, bumpy, and narrow. Expect to spend at least 30 min for going up. So I wouldn't go there on crossovers, only proper 4-4
At the top, there are 2 campsites, 20 meters between each other. Flat, I would say each can accommodate 4-5 campers easily. The view is absolutely marvelous. Extremely difficult road limits the number of people
There is another campsite downhill (it should be at around 400 m altitude - it can be spotted on the photo here) - I've seen youtube videos where people did camping there, it looks very spacious and the road is obviously much easier.