Just my luck: weeks after deciding to do a video on my 'great' Gnomoria strategy a new patch brings changes that makes sliiiiiiightly less desirable (read: horrifically less desirable). Sealing yourself in previously meant you could, eventually, go and harvest the corpses for their armor and weapons at your leisure. With the new way that Kingdoms are valued all that dropped loot spikes your value and means tougher monsters in greater numbers a lot faster. Not dealing with those monsters and their loot becomes problematic and I lost my latest Kingdom (Gankland) very quickly as the two-headed Ogres and the battalion of Mants jostled each other on the way in to my fort to wipe my population of trusting Gnomes. I may have to re-name the kingdom to Mantland.
I'm working on a modified version of my strategy and will post a video in the next week or so showing my catastrophic failure mentioned above, and (hopefully) how to remedy it.