i have 2 acres split in 3 sections and only 2 horses... end of season I always have some grass for them to graze 12 - 14 hours a day.... when rain hits here grass grows real fast, but I always cut the pastures before I let them on it in the start of rain season....
Hope that made sense, our Cushing's horse needs to be kept in a field with no grass with hay or hay cubes soaked for her.
He's super adorable - the coat is a concern, that's a clear pituitary issue. Except I've heard some stuff about how horses with fly masks all the time often will grow thicker coats. It seems silly, but horses shed their coats when the light reaches the back of their eyes for a certain amount of time. That's why my blind horse always has a winter coat. So sometimes being shaded from the bright light (as important as it is) can also interfere with their body's natural cycle.