I've been touring in AU during late spring and midsummer. It's been up to 38-40C.
Leathers and non-mesh textiles just don't work. I tried. You need big vent panels to stop overheating from lack of sweat evaporation. You might get away with kevlar jeans, as long as it's not too humid (which is what I wore before I got some Dainese Drake pants.)
For underlayers I use both the Alpinestars Ride Tech Summer and the Taichi Coolride. I also use cycling baselayers (e.g. Craft brand) when these are soiled. The sweat wicking helps with evaporative cooling, and stops the jacket/jeans sticking to bare skin.
I leave the armour to the outer layer, not the inner. I have never seen anything like what you've posted outside downhill MTB and dirtbike catalogues in Australia. They look like wetsuits! For what it's worth, I also have a set of Dakine downhill MTB knee/elbow crashpads which are supposed to handle sweat and heat, but end up never being worn in summer due to skin chafing.