Keeping a difficult horse fenced?

I have a two year quarter horse stallion. Camanchi is well manner, with a wonderful disposition. We don't have problems with him, with the exception of our pasture boundaries. He is in a pasture with his three "brothers" (our geldings), whom he get along with very well. Unfortunately, Camanchi won't stay! Houdini, we call him. We've been through every type of electric fence we could find, and recently tried a four cord fence, "guaranteed to keep stallions in"... it didn't work. We've even had professionals install the fences. Chi was a rescue horse, who our vet said will never be able to be ridden, so we don't want him stalled; we desperately want him to be able to just be turned out to pasture like he needs. The next step is a barbwire fence, something none of us like the idea of. We just know he'll hurt himself terribly. Is there any other solution?