Well I do have a diplomat in East Continent, so next time a war rolls around I'll be sure to propose it. It could also be done amongst new allies.
1 diplomat alone is probably not goig to be all that fun...
I had an ambassador with maxed out oratory skill, great bureaucracy skill, and I did that (while "trading" or during random RP events), and it took a long time to not yield much of a result. Really you'd want like 6 highly skilled ambassadors at the same time spread through the realm to have much of an impact. And their own diplomats and ambassadors can then come and undo your work for free, though.
