Setting up a Virtual Display to combine 2 Monitors

Hello everyone,

I’m trying to create a virtual display that combines my 2 monitors to be able to play games in full-screen.
I’ve got 2 identical 2560x1440 monitors, the right one is in vertical orientation

So far I’ve tried using xrandr to create the virtual display, but I wasn’t able to set it up correctly.

xrandr --setmonitor CombinedMonitor 4000/597x1440/336+0+0 DisplayPort-1,DisplayPort-2

Creates the virtual display I want (I think). Whenever I launch a game (CS:GO) in full-screen, it picks up the custom resolution of 4000x1440 and stretches correctly, but the content is still only displayed on the left monitor and simply cuts off between the 2 monitors, showing only the desktop on my right monitor.
Setting up my right monitor horizontally and using

xrandr --setmonitor CombinedMonitor auto DisplayPort-1,DisplayPort-2

Creates a virtual display with the resolution 5120x1440 but the problem remains the same and full-screen applications don’t stretch across both screens.

How can I achieve full-screen gaming across both monitors?
Any help or alternative methods would be welcome, thanks!

Manjaro KDE Stable, Kernel 5.9, AMDGPU