Would you just mount the caps backwards on the XY mount, or can you adjust the angles on the ORTF mount?
Unfortunately, just mounting the caps backwards in the XY mount doesn't get you enough spacing. So, I played around a bit and here's what I came up with:
[1] place the 1st XY bar mic-clip DOWN in the bar
[2] place the ORTF bar mic-clips UP in the bar
[3] place the 2nd XY bar mic-clip UP in the bar
The 2nd XY bar won't fit in the grooves of the mount base, allowing it to rotate freely when you loosen the screw cap. This is good.
To run ORTF - just like normal.
To run XY - just like normal, only the 2nd XY mount isn't within the grooves of the mount base. No big deal, it's plenty easy to line it up.
To run DIN - extend the 1st XY bar as far as it will go within the mount. Mount the cap facing opposite how you would for XY. Mount the other cap in the 2nd XY bar and rotate the bar until you have a 90º angle. If I recall, the caps are practically dead-on spaced at 20cm. Nice thing is, you can open or close the angle as necessary depending on room issues.
The only real issue, which was never a problem for me: the mount base rotates through around 180º. The mics set up in DIN are in a different plane than the mount base rotates. What this means is that it's not easy to angle the mics up or down using the mount base itself. I always just rotated the A20S shockmount if I wanted to angle the mics up or down.
Does this makes sense? It's kinda confusing thinking about it without having the mount in front of me. Lemme know...