May be this is not the best place for a meal but to have some siesta when it was really hot, that was perfect: excellent shade and a contact with the rock that remained cool as it had not been heated by the sun yet!
However, it might happen that there is no tree, no rock and no truck! Then you must rely completely on yourself. That was the case on the photo and all we could do was to draw a tent fabric along the car, which gave a poor and hot shade! Not the best bivouac but we could not do better!
Btw, what about menus? Even if canned or dry food make the basis of everyday meals, you can buy excellent bread in places like El-Goléa or In-Salah. Wrapped in several layers of fabric, it will keep for several days, possibly until next bakery!
On the markets, you can also buy yummy tomatoes, onions and fresh eggs.
We once were helped to fix a small break down on the Land Rover by the drivers of one of those large trucks that drive the desert from north to south. After that, they invited to have mint tea and we had an unexpected bivouac under their truck. These trucks are so large that you can almost stand underneath. They offer a very comfortable shade and moreover, they build a kind of Venturi effect and even if there is no wind outside, there will be a gentle breeze under the truck!
Under a tree. When there are trees, they most of the time be thorny: %Acacia seyal% in the North or %Acacia radiana% in the south. Their shade is pleasant but they have very strong thorns. Keep your walking shoes. Beware of getting a puncture on one (or several!) of your tyres!.Of course, you know how to repair a flat tyre, even on a LandRover (that can be scarry!) but it is better to avoid it!
On a trek, we did not have to choose the place to picnic and have a rest at noon. However, on several occasions, we were on our own and I had to look for a nice place. This is not always easy as at noon, there is not much shade.
Along and under a rock is certainly the best spot. When this occurs that is excellent but if it is the first time you visit a place, you find a suitable place by random!