backing up constantly!

I agree with Hrt4Dressage ... dressage whip is the way to go.. don't take no nonsence.. and chances are you wont even have to use it.. but if you do.. tap tap tap tap on his hocks are going to annoy him enough to move forward away from it...

I was at a show on Sunday, and there was a couple people in there with barrel horses to help them relax so they didn't think that being hauled meant they were going to run, and a 4 y/o grey gelding would half rear up to get away from the bit. I think backing does the same thing?

It can, even with a horse that has otherwise never reared/bucked, etc. Especially with a horse that gets nervous or upset when disciplined (like, every single TB).