here's an idea. in the wild, mares always take a buddy mare off with them to watch over them while they are in labor. if you have another stall within eyesite, you might try putting whoever her best buddy is in that stall.
we tried that once with a mare that was 2 weeks overdue and had been waxed the whole 2 weeks. within 2 hours of putting her buddy just outside her stall, she foaled. coincidence ? maybe. but it does go along with their instincts. they are vulnerable during that hour. they can't protect a new baby very well for the first hour. hence the buddy system to help keep predators away.
just a thought. good luck. she looks like a pretty nice mare and a great color. so glad you saved her!!!!