Clay soils and 90's low 100's shouldn't be a problem, you're describing much of the SE US and O.s. does fine here within it's low temp parameters. How dry is dry? Where are you located?

O. fragrans did well in my sunny back yard in hot but humid Gulf coastal Texas. Really bad unamended clay could be a problem.

Zone 9b in Antioch CA, the soil is clay, I can keep the soil somewhat moistured with some mulch and 1/3 soil amendments so it won't dry and crack ..and thx

O. fragrans is considered drought and clay tolerant in SoCal when established. A partly shaded location, especially in the afternoon, would be helpful, but not required. Tolerates basic soils, as long as not too basic.

read the link in regard to planting in clay ... no amendments is the usual suggestion ...

you dont really choose trees based on the soil ...as soil is more of a planting and watering issue ... [we arent discussing bog trees.. eh..lol]

and do keep in mind ... no transplant is drought resistant until fully established.. and that could be a couple years ...

and i would highly suggest small transplants ... around 4 foot .. unless you are having it done professionally with warranty ...

finally .. TIMING is of the essence ... nobody but the pros.. plant in summer.. with high success ... newbs ought to be looking for periods of dormancy ... i would guess that in your zone.. that would probably be your version of winter ...

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub