Have you tried a cooling vest? I got one of those phase-change dealies this summer and it really made things bearable compared to when I was almost fainting after a 30 minute walk. I’m actually still wearing it now even though things have cooled down, since it’s more comfy and I end up sweating a lot less.
That’s actually a myth (it was quite successful in Japan), but a widely circulated one so I don’t blame you. Textbook example of “a lie can travel half way around the world while the truth is putting on its shoes.”