This and 0025394 sure do seem to be related, or even the same bug.
--eon_force_display= put it on the correct screen for me.
BUT: The mouse input problem persists.
If I am on screen 0, it is fine. Any other screen (and the game likes to default to 2 which is the third monitor) you can't click anything.
I need to run it on screen 1, that is the center monitor.

The workaround is to use the keyboard to put the game in windowed or fullscreen-windowed mode. Doing this has a somewhat annoying side effect, the hardware cursor is rendered on top of the game. But it is playable.

I am using Nvidia's mosaic feature to use 2 gpus and 3 monitors.
The physical layout from left to right is.. 0 1 2

The game also likes to warp the mouse all the way to the right of your desktop when you hit esc, or open the map. I thought this may be interesting to note considering the game also likes to move itself all the way to the right on launch without eon_force_display.

NVIDIA 352.21 arch, I3

TLDR:
Mouse works in fullscreen if the game is at 0,0 on your desktop geometry. Otherwise use windowed mode.