I'm not sure how this would be too different from any overly ambitious realm. It is common practice for many realms to paint their enemy as evil. I'm not sure how what you're planning would be all that different. Or even different enough that anyone would notice.
I think the difference is primarily a matter of intention. Most people, I think, will be willing to betray an ally if they are put in a tough situation—under duress, as it were—but this realm would, essentially, be actively looking for ways to get ahead through betrayal.
And yes, as I said, part of the point would be to see if anyone noticed.
