This is probably more a case of "setting" than "location", but that seemed like the best categorical fit.

The biggest question to be answered, in my opinion, is whether or not we're talking the same levels of conflict. If we still have massive armies involved, then Helmer, Picket, and the rest are all still probably soldiers. On the other hand, if the wolves, Wrongtreaders, and such are just outlaw gangs, then our bucks would probably be more like marshals, sheriffs, deputies, etc. The Terralains seem like they'd work best as Native Americans, but maybe that's just me.

Obviously, you'd have to replace the monarchy system with something more culturally appropriate. Maybe Bleston ran for governor of the Natalia Territory only to lose out to his younger brother Jupiter. Perhaps Jupiter left behind a will that nobody can find, leaving various parties scrambling over his considerable property. Garten could be a crooked lawyer, forging documents and exploiting legal technicalities to make Winslow and/or Bleston seem like legitimate claimants to the office once held by Jupiter.

The secret citadels and First Warren would be towns or cities on the frontier, with the various lords serving as mayors. Again depending on the conflict scale, the Lead Captains would likely be either sheriffs or commanders of forts adjacent to each town. Daggler would be a corrupt one of these. Akolan would be a mine worked by slave labor, the predators unaware that some of their slaves have discovered natural tunnels providing a possible means of escape.

And, let's face it: Heyna would totally be that society lady in a fancy dress and feathered hat, all beauty and grace and charm-up until she whips out her custom made pistol.