sorry for curt reply yesterday, was posting on the mobile.
As above the monkey bone works well, but wont work with an IS caliper like the XTR M965 I have.
The Speedbone cant reach out the back from the internal caliper mount so that wont work as is.
I use the torque bar on the speedbone, shorten the speedbone for fitting and a little filing to transfer the torque to the caliper mount within the rear triangle.
Works fine. There's the tiniest of movements up or down to the corresponding frame contact point as the gears cross the middle range but a little bit of grease prevents any creaking. Works a treat and has done many miles like this including in Luchon.