work on half halts, get her to round out her back at the walk before you move on, the more relaxed she is the calmer she will be, I had to do this with my Thoroughbred for months.
If she is crazy on the trail, lunge her before you get on and work her in the pen before you take her out. A lot of horses will act completely different outside of the pen immediately, my horse did, so start slow, once she is calm and working inside the pen walk, trot and canter her round the pen, using it as a tool to get her to bend and round out and calm back down. It may take a week, it may take a month, get her used to calming down outside of the pen before you take her on the trail.
16 year old TWH Mare named Ginger
3 year old APHA Paint Gelding named Fox.
RIP Evie (Clydesdale) 7.29.09 & Magic (OTTB) 2.23.10