I ride motorcycles a lot in the 90plus degree weather in South Louisiana. I ride with an EVAPORATIVE VEST, soaked in water. Cools you off as you ride.
For fishing, I have a base layer of LD Comfort T shirt, Evaporative vest, and Columbia white long sleeved shirt. Keeps me cool! After a couple of hours, resoak the vest in water, put it back on.
A hat of course, and either ANTHELIOS XL 60 SPF or MDSolar Sciences ULTRA MINERAL SCREEN, SPF 50+. Both of these are highly rated sunscreens....the first one with 3 blocks for UVA and UVB and the second with Mineral blocks, Titanium Dioxide, and Zinc oxide.
Oh, and Costa Del Mars or Maui Jims....full UV protection with polarization....gotta protect those eyes!!
I believe that covers most everything!