I have ridden and run a lot in very hot parts of Oz. (ie 30 – 40ºC desert, and humid rainforest)
I reckon all that sort of stuff is a waste of time. Keeping direct sun off your head is more effective.
A wide brimmed hat* and a Buff to protect your face from the sun does the job for your head.
Drink lots of water and wear loose fitting cotton so your sweat cools you. The best place for any water is inside you, not applied to your outside.
Sunscreen stuffs up the benefit of sweating, so avoid using it on body parts that can be covered up. Long sleeves which can be rolled up are handy, and long shorts which protect the tops of your legs.
*In Oz helmets are compulsory so we used to extend the peaks of our helmets or wear legionnaire style hats under them to get max shade.
Edit: you won’t win any beauty contests though… 🙂