Cushings is a very complicated disease. My last horse had cushings and it was a constant battle. Here are a few suggestions.
Keep her on the Chaste Tree. Sometimes it takes a bit to work, you may have to up or down her 'dose' but it should help.
Start her on a low starch diet. Cushings horses are usually insulin resistant and therefore a low sugar, low starch diet is best.
As others have mentioned, founder is always a threat. They haven't been able to link one to the other (cushings to founder) but they are linked. Almost all horses that have cushings eventually founder. Watch his/her pasture intake and lock that grain up tight.
As far as hair management, its all what keeps your horse comfortable. If they are sweating, its time to clip. Give them the best chance they can to shed the hair. Our cushings horse was a paint and would only shed the white (strange but common) so we had to clip his brown. Always leave enough hair for protection.
Exercise can really help and unless your horse is severe there is no reason not to ride/drive/lunge.
Keep in contact with your vet and farrier. They can be a huge help when things change. At some point she may need to be on actual medication.
Do your research. 5 years ago, chaste tree was unheard of. It eventually made monte more comfortable. He wouldnt even shed the white without it.
Oh and lots and lots of water.
Good luck! Cushings is difficult but not unmanageable.