I use a lifeguard hat, I thought it was expensive at the time but it makes being out in the sun bearable. I usually wet it down for extra cooling in the AZ sun.
You feel silly at first wearing one but after the first time your neck gets burned because you didn't have it you stop caring how it looks. The only thing more protective would be an umbrella.
https://www.amazon.com/Super-Lifeguard-Summer-Safari-Gardening/dp/B001846GPK/ref=pd_sbs_193_1?_encoding=UTF8&refRID=MR5JGTJKFH99ZQK2VEQF