Canvas scaling for triple monitor setups (NVIDIA Surround / AMD Eyefinity)

Canvas in Screen Space render mode always takes up the whole screen. When the resolution is changed, Canvas Scaler will make sure the UI elements have proper size.
This works fine for most of the resolutions - until we go wider than Ultrawide (21:9).

Typical triple FHD monitor setup has an aspect ratio of 48:9 and 5760x1080 resolution (when using NVIDIA Surround / AMD Eyefinity the monitors are seen as a single display). Games optimized for "triple-head" display tend to keep their UI on the middle screen, as UI elements in the outer corners of side screens are difficult to track without turning head.

The question is - is it possible to have Canvas limited only to middle screen (rect of x:1920, y:0, w: 1920, h: 1080)?

Will it require using World Space render mode to specify Canvas size and a script to keep it always in front of the main camera?