Easy, I live a couple hundred miles from the equator and I spend a great deal of time in the Caribbean. Coppertone Sport SPF50. I comb it through my hair. It dries mate and behaves like a light gel or mousse. You can spray after or use another products if necessary...

Just be carful not to let it get too close to the attachment as it, like most wax works, gels, putty, will cause your attachement to come undone faster. There is a sort of a moisturizer oil type of ingredient in these things. Conditioner also has the same effect.

Other products mentioned here work OK but if you want 100% protection from the an intense blazing sun.....