Because we're looking at the weird western as an inspiration, it may help us reformulate our views of the traditional fantasy setting in comparison to it.
Most generic campaigns have hordes of goblins, orcs, and kobolds running around in clans making some folks wonder why they don't just overrun the nearby civilizations. Westerns in general give us an answer: Native American tribes and rival gangs of outlaws (organized or not). Sure, some of them worked together -- but often times they did not, and even fought against one another, allowing some (but not all) towns and villages to survive and even thrive as the various military and civilian bastions of civilization eventually extended their influence.
It even allows us to showcase these non-human races in a sympathetic light, while retaining that "otherness" essential to a weird western. They can even drop hints about some dangers that strangers to their lands are unaware of.
Of course, this has been done before in a number of supplements. But it may help to keep in mind the historical roots and genre tropes for a good grasp of what to do in unusual situations.
Creatures Fierce and Fantastic
Some of these dangers are traditional fantasy creatures, twisted to fit the western setting. The 6th Gun has animated skeletons, earth golems, gryphons, werewolves, and loa but tweaked to fit western sensibilities.
The skeletons are resurrected from the graves of dead soldiers and fortune seekers, the earth golems are animated by the souls of those killed by one of the gun artifacts, werewolves are mentioned in passing, while loa (and the bokors that serve them) are given more significance.
Of course, my favorite treatment was of the Lightning Gryphon as a dangerous hazard along a deadly path -- and hinted at as an inspiration for the Native American myth of the Thunderbirds. Much like the meme earlier this year about a fresh take on old monsters, mashing up D&D monsters with the old West can surprise and reinvigorate well-worn monster tropes.