yeah i run triple 27's 5960x1080 bezel corrected for games like pcars and gsce, but for AC i use 5760x1080 and use the triple screen app, adjust for bezel thickness and angle.
i used to measure my spinner width as 1500 ans spinner distance was adjustable between 650 and 900 depending on car, i was convinced that total width of screen width, in a horizontal line was what was required. my settings were all wrong as my speed was way to fast at the time. i did note the ratio between width and distance, approx 2:1, so whether its 1500 width and 750 distance is the same as for example 600 width and 300 distance, the picture willbe identical.
anyhow what i do now is leave the spinner width at 600 ( actual horizontal width in mm of center 27 inch monitor) and adjust my spinner distance around the 400 mark (actual measured distance is 525mm from eyes to monitor, just cant enjoy the game like that) At 600/400 ratio (3:2) it feels pretty darn good, sense of speed wise, then adjust the seat forward or back, up or down, left or right to suit depending on car.