Thinking of a stunt bike why not the F800GS?
 

This guy was so amazing on the 800GS he was doing things that broke the laws of physics!

I was told the bike is completely stock, he just let a bit of air out of the tires and tore it to shreds.

I saw him last year at the races in Salt Lake City. Its on again next week.
I think he will be there.
World Superbike Races at Miller Motorsports Park over Memorial Day weekend, May 29-31, 2010.

This why I don't like to buy second hand bikes if I can avoid it...

Google around for Stunt Vids
 

Google Christian Pheiffer (not sure on spelling). He is one of the best Euro stunt monkeys. Christian also uses an F800.

That UTube doesn't really show what can be done, not enough room to really let it all hang out. It gets far more extreme. WSB and MotoGP often feature these guys as between race entertainment.

Your right I've watched a few other video's with this same guy riding in a bigger space much more entertaining. But at the same time I was very impressed with what he could do given the limited space.

This guys name is Teach McNiell. He really didn't have a whole lot of room to work with, but amazing none the less.

Sounds like a blast I'll have to see if I can make it out there

I've done some of those things on my 1200GS, but never deliberately and with my own variated endings. Ride safe.

:D