Stinger most of thoe people that write those articals either work for the company or are paid off by the company, don't see much science in there claims, lot of hypnosis but no real science. Although they do say it helps with chaffing. Besides it's imported. Do you trust where it comes from? I Don't.
The problem is you are not stopping the heat from penetrating your garments.
Keep the Sun rays from hitting you, that is what will overheat you, find an insulating clothing that will keep the rays from heating your skin, sorry guys poly is not a great insulator, they call it Under Armour for a reason.
Breatheability to vent off heat is paramount but it must also insulate you from the heat. Much like a cooler in the sun you put ice in there it stays cold, you put a temperate body inside sun insulating clothing "and" allow it to breathe you'll stay cooler, longer, with less water useage than trying to keep an evaporative cooling action going.
Ya Under Armour "works," works ya two ways, first you pay for it, than to pay to keep it going...
Not telling you what to do but I would look elsewhere for clothing to use on an adventure they could span more than a few hours in the heat.