On Friday, April 6, 2018 at 10:06:25 AM UTC+2, Tosspot wrote:
So, the Surly Disc Trucker has chainstay IS mounts[1]. I have;

A rohloff hub with TS axle
An OEM2 mounting to go with;
A speedbone
An external gear mechanism

I'm thinking this is beyond even my Bodgit & Scarper(TM) skills. Is the
only option a long torque arm on a standard plate? Which looks like it
might get in the way of the external shifter.

[1]
https://bicyclehabitat.com/images/li...y-242015-1.jpg

You only need some kind of mounting hole(s). I converted my singlespeed to a Rohloff hub equipped bike for winter evening rides. Mayby this gives you some ideas:

https://photos.app.goo.gl/b8PoQGQWng8OdXnJ2

Lou