I should go out and study the native wild plants, and copy their species in garden varieties. If they survive on their own it may point you in the right direction.
Otherwise Orange and Lemon Trees, Date Palms spring to mind.
Make plenty of compost and mix with soil, and put each plant in a large container. It will then get the maximum benefit of the water you give, which seems to be leeching away into the surrounding ground.

Thank you for your kind reply ! Will do.

I've been thinking- Chaste tree to cast shade & endure the dry heat... Very pretty, too !

That container idea is BRILLIANT ! I dug up some salvia I had planted that looked starved to death & it appeared that leeching was exactly what was happening- I moved them to a more formidable location & went instead w lambs ears & caryoteris - Seems to be faring better.