And this is the benefit of the internet, everyone can state their case and take from it what they want. Hopefully somewhere in that process the OP will get some advise that makes sense to them.
My previous mare would rear in crossties and become extremely dangerous any time she was tied, She came to me like this, and my fault for not seeing her tied before I bought her. So I fed her and then tied her in her stall while eating, at first I would untie her as soon as she was done, and then I gradually increased the amount of time I left her tied for after eating. Then I moved her to cross ties, and no I did not feed her in the cross ties. I let her be for a min or two, then slowly increased the time. She leant and it worked for me.
Very sensible approach to the problem. Horses can get used to anything given time and a little patience. Well done!