That's the kind of fly mask you'll need. I use a product called Filtabac on Ricky's snip. It is a specially designed horse sunscreen, but it also works as an anti-bacterial cream, antiseptic, and wound protectant. It really is a great product, and since I've been using it Ricky has never been sun burnt. He only has a large snip but I put on the stuff daily and he only has to wear a fly mask on the hottest of days.
I know I sound like I'm raving about this product, but I really like it. I don't know if anyone else has had any experiences with it though? Filta-Bac
I'd definitely give it a go WS. Its a really good product and if I have no antiseptic spray or anything handy, I just plonk that on and its great. Its really good at litte shows too for horses with snips. Just apply it carefully to the white area, and its bright white and protected from the sun on those long show days :)
Your full fly mask with nose cover will probably help, at least some. My mare had a pink nose that I put Desitin on and it definitely helped. Tara doesn't have any pink skin, but I do use Vetrolin Shine wit sunscreen (there's other sprays on the market that are actual sunscreens, not just coat conditioners with added sunscreen...I think Absorbine's Santa Fe line has one). That might help some too, at least for areas not around his face :)