For sure get yourself a pop up tent! Even if you use chemicals that can be used in direct sunlight, do you really want to work in direct sunlight? Makes doing what is fun for many of us, un fun quickly.
Someone earlier posted my idea - Poorboy's world products (sold by AGO) are designed to be used in direct sunlight. I just did two cars this past weekend with their polish, and had no issues. It was a sunny 70+ degree day in DC. I'd definitely recommend looking into their line, and the cars look real nice.
I am not worried so much about sun actually....My driveway is fairly shaded but the con of that is about 4 very large pine trees. When the wind barely blows I have needles and other small things landing on my car or blowing around..But I appreciate the product referral.