Yes, I think I can. It'll be tricky, but I'm moderately confident.
Go ahead and do your raw processing first, then post the SOOR for me and we'll discuss the background.
Has this problem always existed, for as long as you've had the action? Or is it something that has started happening more recently?
Also, can you do this for us?
Just use a two-colour gradient - dark to light. It looks a bit weird having that dark circle behind his neck.
Otherwise, this is good. Now zoom WAY in and start masking properly.
As I mentioned earlier, I used a radial gradient rather than a linear one, but I think what you've done here will totally work. Go ahead and start your precise masking now.
No no no!!!!! You don't use FastStone any more, because you have Bridge.
FastStone is great, but Bridge is heaps better.
http://www.damiensymonds.net/bridge-video
No, don't do the marquee thing. It's limiting yourself too much later, in terms of print shapes. Take the time to mask the background around the WHOLE horse.