You described how the software does not support multiple displays. What are you unsure of?
Retaining dual screen workspaces (at least) can be worked around by opening the software and immediately shifting the intro screen over to the secondary display before opening a project.
I have dual screen workspaces saved that repopulate exactly how I saved them. But I have only done this with two displays. Other users have reported problems getting this to work when using more than two displays. My third display is dedicated to a separate system that I use for supporting material like the manuals, internet research and Photoshop.
The issue is that multiple screens are not officially supported so all of the glitchy behavior is written off. For instance, if you open a new project while the software is already open, sometimes you can retain the multiple screen layout if you move the setup screen over, other times everything reassembles and dumps out onto the main screen. If something acts up Toon Boom does not officially support multiple displays so you have to live with things that would otherwise receive attention. On our end it is extra important to have a strong video card and plenty of RAM.
The workaround is to open existing and new projects from a state of closed software and immediately shift the intro screen over to the secondary display.
I mentioned supporting multiple displays in this context because Focus on Mouse Enter does not support floating displays while spreading view windows out on multiple displays requires the use of floating displays.