Hey astro; I think you're doing it wrong.
Green Hills is way too open for effective farming.
You should try killing gargoyles (and maybe skels) under Ashford Abby. When you first warp in, there's an opening behind Necro Munne's(?) building. Just keep killing gargoyles till you hit Green Hills, then turn around and repeat.
Lots of pushover enemies is the key to holiday farming.