My space flight project is one that I've thought about modifying to do something similar. Mind you, I've only thought about it, and have not tried any implementation. I really haven't used multiple monitor setups enough to fool with it.
It being a RPG utility, I could run a setup where the gamemaster would have one screen showing all the action and another monitor which would have only what the players would have access to.
I assumed that since only one screen could be drawn, one would just make a double width screen, draw the desired details on each half and _SCREENMOVE _DESKTOPWIDTH - _WIDTH(0)/2, 0 {or whatever ratio desired} to split between the two as a work around for not having two separate screens.
Alternatively, upon a certain condition being true one could move the screen at will with a _SCREENMOVE that alternates between 0 and _DESKTOPWIDTH +1
...well anyway, nothing would beat a try, but a failure...