Have you thought of trying 'Snuggy Hoods?'. They are quite expensive, but manage to keep the whole head, neck and shoulders clean, warm and rub free. I have a 'silver white' Spanish horse who would rather be brown with dreadlocks and this helps! the Zip up ones are easier to fit, and they wash and dry really quickly!
He is also living out 24/7, having kept him stabled at nights last winter, he has decided he would rather be out with his well rugged friends!