[DylanVK]

As already mentioned... can be done, just isn't ideal.

Products will behave differently, flash off prematurely, dry too quick, etc due to the added heat on the panel.

Work earlier in the day or later in the afternoon/evening when the sun is low in the sky. Use shade as much as possible - even consider investing a little $$$ in a pop up shelter to shade the parts of the car you're working on. For $100-$200 you can find a nice 10x10 pop up at places like Dick's sporting goods... obviously not big enough to shied the entire car, but you can move it to provide shade on the areas you're working.