Hmm, maybe that's promising, then, if one end's free.
How much thread have you got to work with at the end of the bolt? I remember 'locking' two nuts together for getting out stubborn cylinder head studs (sometimes combined with penetrating fluid and/or heat).
Even if you don't have much exposed thread, maybe there's enough space to weld a nut to the end of the bolt and use the breaker bar to free up that end, then cut the nut off once the bolt is able to turn a little along the full length of the shaft? At that point, hopefully a bar on the head, or a clamp, will be able to remove the whole bolt...
No kidding :-) It was just a random thought and I wanted to conform that someone knew for sure that these bolts weren't somehow different.
Could be worth a try, although it's amazing how much force stuff like this can need - and I suppose there's a danger that the clamp might just distort the end of the bolt, rather than forcing it to slide along its axis.
cheers
Jules