Here is an example of similar hardware I have. My Tobii EyeX is mounted to the center monitor (over the ASUS logo). I’m currently running (2) nVidia GTX 1080 Founders Edition in SLi.
NVIDIA G-Sync Surround Impressions: Using 3 ASUS ROG Swift Displays
I would even be happy if I could just manually set Tobii EyeX to work with a resolution I set and with a top and left position to center 2560×1440 with a top of 0 left position of 2560.
-Ken