With these settings, the playfield is on the correct monitor but the backglass is behind it (in PinballX only) but when loading a table it puts it on the correct screen. This is definitely a PinballX issue but I don't know where to go from here to make it correct on first launch. Also, I tried AutoPositionB2S=False but it didn't make a difference.
[Display]
Monitor=1
rotate=270
windowed=False
WindowWidth=1600
WindowHeight=900
WindowX=0
WindowY=65
PlayFieldBrightness=230
WheelTextColor=ffffffff
WheelTextOutlineColor=ff000000
InfoTextColor=ffffffff
InfoTextOutlineColor=ff000000
FilterTextColor=ffffffff
FilterTextOutlineColor=ff000000
MenuColor=ffffa500
WheelAutoCrop=True
FullScreenWindowed=True
[BackGlass]
monitor=0
x=0
y=0
width=1600
height=900
AutoPositionB2S=False