To the Coat thing...
A Compromise between hot temperature, and öhm... coolness would be a light Color.
Like White, Beige or a light Brown. (other light Colors (Blue,green) work as well but due Westerntheme we focus more on earthtone Colors, besides a Babyblue or Pink Cape over a Mando wouldn't funtcion. People would look for the Hello-Kitty-Logo.)
The Touraregs and other Nomadcultures of the Saharadessert and the middle East are wearing mostly thick, white Robes.
In the first Place the bright Colors reflect the Sunrays and not suck the light like a Black would do. Thus its not so hot under it.
And in the Second. Well its the Desert... In the Night it gets cold to -40°C
And atleast. You wont dry out so fast.
Funny Fact: In the Sommer I'am used to wear a bright-beige Trenchcoat over my (normaly) black-clothes - instead of wearing shortpants XD
So Conclusion:
Try a Cape/Coat/Poncho in light Colors
beget'ye