One permaculture strategy would be to first plant more drought tolerant plants around them to provide just a little bit of shade.
The usual rules don't apply in a hot desert; even sun-loving plants will appreciate partial shade.
Yes, in general grapes do well in hot dry weather, but a hot desert is testing the limits. They are going to need irrigation, at the very least. Surrounding plants as a windbreak helps to reduce evaporative losses also.