PSA: Modern nVidia drivers refuse manually specified modelines if you disable EDID, and it apparently hard-codes "primary = leftmost" at the xorg.conf level now, making MetaModes useless.

To lock your resolution, leave KScreen 2 enabled for the "primary != leftmost" fixup and patch your X server or Wayland compositor, write an LD_PRELOAD hook for XRandR APIs, or buy a hardware EDID emulator.

To prevent hot-unplug from jumbling your outputs, patch your compositor or buy a pass-through HDMI dummy plug.