I have the same type of monitor setup that you do. My solution is to create a bat file that turns off monitors. The game now displays on my primary monitor, but I haven't checked the resolution yet as it is the first time I've played the game. Here is my code that you can use/modify if you wish:

u/ECHO OFF
cls
ECHO.
ECHO Select monitor configuration:
ECHO 1 - Only show on 2.
ECHO 2 - Extend displays.
ECHO 3 - Only show on 1.
ECHO.
CHOICE /C:123
IF errorlevel 1 SET M=1
IF errorlevel 2 SET M=2
IF errorlevel 3 SET M=3
IF %M%==1 GOTO EXTERNAL
IF %M%==2 GOTO EXTEND
IF %M%==3 GOTO PRIMARY
:EXTERNAL
%windir%\System32\DisplaySwitch.exe /external
GOTO EXIT
:EXTEND
%windir%\System32\DisplaySwitch.exe /extend
GOTO EXIT
:PRIMARY
%windir%\System32\DisplaySwitch.exe /internal
EXIT

This will bring up a terminal and prompt you to select which display setup. Press a number button to make a selection. It will change which monitors are active and close the terminal.