it does take alot of time,and every horse owner feels at one time that their horse is too much for them, that they should sell the horse etc. I know for a fact that I have, and at times I've even made out a for-sale ad for Sonny. But I worked through his problems...and gosh did he have ALOT of problems.
Sounds to me like you still may be asking a little much from Chance, more than she can give you at this time. It might be that Chance, like yourself, is not too confident and needs good assurance.
You also said that she is extremely bonded to you, and if she truely is a one horse, horse than she will give the world to you simply to get love and attention.
The rearing could be a dominance issue, it could be discomfort, or something is scaring her. (i'm sure there are other things that can cause a horse to rear...but can't think of any). I guess it is possibly for someone to work with her when your not there, but it seems almost unlikely. I thought someone was working with Sonny for a while at the old stables, but the more I realized, I wasn't getting on him to correct his poor leading manners, and he was slowly testing and testing me.
HAF, I know you like Parelli somewhat so here is what they say about rearing:
"Horses tend to rear for two reasons: 1. They are being held back. 2. They feel trapped or cornered. Usually a more flighty horse tends to rear, and also makes you want to hold them back. They begin by tossing their heads, and if it gets bad enough they'll rear. Think of it this way, they have a driving, forward desire yet there's something in their mouth holding them back. If you hold back strong enough there is only one way left to go... UP! Some people think horses rear on purpose to intimidate the rider but something important to understand is that the horse is thinking like a horse. He's naturally a fearful, claustrophobic animal whose main defense is to run away.
We don't believe in punishing horses for rearing, mostly because it's a fearful reaction that is often caused by the handler or rider, albeit unintentionally. Once you change your approach, regain your horse's confidence, and stop using two reins to control your horse, things will change dramatically. You can learn how to do this using our specialized techniques. The best place to start would be The Seven Games DVD - The Secret of Teaching Horses; then go to the Calm Ride DVD. Both of these DVDs will give you new and effective strategies right away. After that you should study HorsenalityTM so you know more about your horse and then Natural Attraction to learn how to get him to want to be with you instead of trying to get away from you.