Set up default different windows positions ?

[WOWBOX40]

I run many monitors and ive used this software for 3 years now. Maybe this is what you are looking for. I think you need to run a individual wow install for each window mode wow you want to run, possibly. Its possible to set it so f.ex if you launch microsoft word..it opens on monitor 2... if you open blabla it opens on half of monitor 1 etc. You should be able to open f.ex 9 wow windows on a monitor aswell. Lots of options.

https://www.actualtools.com/multiplemonitors/
It has a 30 days try before you buy feature.

Why not just use isboxer to set up your windows though. Its easy and its an allowed software. If you happen to run multiple games and is able to press buttons in them without using some kind of software that makes it possible...blizzard will notice, as you obviously is using some external solution = banhammer incoming. They are also able to track keypresses down to the milliseconds.