Something I have found that works well for my Paints, is Desitin. Yep, diaper rash oinment! Even better , and cheaper, is the generic desitin you get at the dollar store. The zinc in it protects from sunburn, while healing any skin issues already present. And it sticks and lasts wayyyyyy longer than any sunscreen I have tried. Last summer was my first summer trying it, and I might never go back to regular sunscreen. I only need to use it for noses/faces, but I have a friend with a Cremello mare who has used it on other parts of her body.
No hour of life is wasted that is spent in the saddle. ~Winston Churchill