This baselayer won't overheat you
I never would have thought that a baselayer would be a good thing to have, but a crash where I got road rash on my back showed me otherwise. An extra layer might have spared me a week of road rash healing.
But...a baselayer for hot weather? Crazy! But not really. The mesh construction lets air flow freely, helping keep me cool. Most telling, my torso feels reasonably dry during the ride but when I take the jersey off it's soaked. So the baselayer transfers sweat outward.
The material's stretchy, so as small as these are they're more forgiving than they look. But don't wear these minus the jersey unless you want weird looks.