Hi,
This is what we do for the better use of 2 monitors:
1 - Open one session with audio and webcam enabled and minimize the presentation, so the webcams will take all the available space
2 - Open a second session without audio and webcam. In configuration, save data we disable see webcams and screenshare
3 - Make session 2 the presenter and upload any presentation
4 - Put the browser of session 1 in monitor 1 and session 2 in monitor 2
It takes very little extra bandwidth as the session 2 will only use the bandwidht needed to change slides.
On monitor 1 we can see the students webcams and take care of the chat