My second monitor actually is a good bit smaller and also offset, which is why I didn't even want to try spreading it across both. And yes, my hope was to get it to where I could have the game fullscreen on just one monitor, effectively ignoring the other one. I'm able to do that with most games and didn't expect to be unable to either give the game focus (preventing the mouse from leaving the game area unless alt-tabbed) or to configure alternate map control keys.
However it should be moot now, I read up more on the EEs and they seem close enough to what I'm after and they're currently on sale on Steam, so I just picked them up and downloaded EET.
Thanks for your help, though, hopefully if anybody else winds up in this position they'll be able to find this!