I hadn't really thought of that, but I can see why the clamps present a problem. It's one thing to play around with alternate tunings sitting at home, but on stage you really would either need multiple guitars, or at least two and a roadie to tune them between songs. If you could afford roadies though, I'd think you'd have more than a couple of guitars.
I'm pretty sure Mark Knopfler has both.
Not that I've played with alternate tunings... or that I can play all that well with standard tunings...
Aries
~Sign of the Rams