FIXED! VKB T-Rudders Not Recognised by Squadrons
Firstly, thanks go out to 'Tuesday John' on the VKB forums for pointing me in the right direction.
It seems that the SW:S dev's made a very strange decision on what HID controllers they allow you to bind, which is why our button boxes or MFD's don't work - that is, that the devices have to have an X and a Y axes to be detectable.
By default the VKB only has a ROT X axis, and thus, it wasn't recognised.
We don't need to use VJoy + Joystick Gremlin anymore (which did work btw) and it's safe to flash the T-Rudders to the latest firmware.
I've tested this not just in SW:S but Elite and DCS and the change you have to make doesn't change any of your existing bindings, it's just that all we're doing is adding the two non-existent X and Y axes just to get the rudders to show up in SW:S because of their ridiculous filter.
See the image below, (flashed to latest first, though probably not necessary) and follow this procedure:
1. SAVE the current (default) PROFILE. This is your backup, although if things to horribly wrong, just use the TOOLS -> DEFAULT to put it back to factory settings (you'll need to do a calibration after resetting).
2. ADD in the fake X & Y AXES by ticking the 3 boxes I've highlighted for each axis.
3. SET this to set the firmware on the T-Rudders
4. SAVE as a new PROFILE (to save you having to do this again after your next firmware update).
... and that's it.
After you do this, open up GAME CONTROLLERS in Windows and see that the T-Rudders now have an X and a Y axis but neither do anything.
Close that and launch SW:S -> Go to OPTIONS -> CONTROLS, scroll to the bottom and see that we now have 3 devices recognised, and one is the VKB-Sim T-Rudder.
You can now bind the controls as you wish - the pedals still bind as ROT -X and ROT -Y but that doesn't matter; it's just SW:S is fooled into accepting it now because it has an unusable X and Y regular axes.
Hope this helps!