Have you considered that someone managing to reclaim Drakwald is so unlikely that if we did a job for Nordland and Middenland and, as payment, asked the two EC's to sign a contract stating that if a force that we command reclaims the Drakewald for the Empire they would cease the land to us and support us becoming the EC of the Drakwald ... They'd probably just go along with it.
It would seem impossible to them so they'd have to think "what's the harm", our services are actually costly enough to be noticeable even on their scale if we actually charge full price, at this point we've probably done enough for them to like us, and, particularly important ... Pre the Drakwald being cleared I guarantee you both EC's would prefer it belonging to a new friendly EC and mostly clear of monsters, then technically half belonging to them but in reality belonging to monsters that do nothing but invade their actual land and kill their citizens and cost them money.
If we put any effort into diplomacy beforehand, especially with our ability to lie and the protector coin, considering how unlikely we are to pull it off in most peoples eyes, how beneficial it would be to everyone, and the fact that the current situation benefits basically no one .... we could probably get most people who matter to agree in a legally binding manner to back us becoming the EC if we pull it off.
Afterwards might be a different story, jobs already done, suddenly the land is worthwhile, suddenly votes are at stake, etc, etc, but beforehand I can't imagine most of the people with a say in the matter being hard to get to go along with us on this.
