If it matters any you can't really zoom out when you have multi-monitors enabled.
The screenshot was fully zoomed out. I just wanted to see what it looked like. I can't imagine playing it that way with everything in the far corners like that.
I didn't think of looking for any ui scaling or whatnot options.
With nVidia in the nVidia control panel you click on "Configure Surround, PhysX" in the 3D Settings. Then you check the "Span displays with Surround" checkbox and that lets you pick monitors to use as a single monitor.