Get a 1ME or 2ME switcher. Activate the DVE and crop a 16:9 source to the 1:2 you need..
Make markers for the cameraman on his preview screen so he has a guide where he needs to keep the speaker between..
The powerpoint might be a issue to get left justified.. But depends on how the content is made..
Maybe just go a 2ME and use Supersource to fix that issue.