Uhh... well, the only way to definitively answer the question is to try it. So you can let us know.
If the box in your Character Set is not checked, the default behavior of ISBoxer is to force the game into a window if you have multiple Slots in the set. For a single-Slot Character Set, it's never forced into a window. This is regardless of whether you have a Window Layout or not. To prevent this behavior, you can check the box in your Character Set to block it. This was made the default after people kept finding out that they couldn't launch multiple full screen game instances. After the first one is up, they would all fail to set up the full screen game instance. From what you're saying, though, it sounds like you haven't had that issue with multiple full screen game instances.
So let's say you get past that particular issue. Video Feeds are probably not going to work in full screen mode. Part of the problem is that when you alt-tab, a full screen game window usually stops rendering at all (unless the game is designed to switch into windowed mode and continue rendering, but this is not typical).
So no, I don't think that this idea is going to bear any fruit for you. You can still try it, but there's my thoughts.