The frontier as isolation engine
Isolation is the western horror's primary resource, and it must be physically built into the setting. The homestead is two days' ride from the nearest town. The canyon country has no landmarks. The storm closes the passes for a week. The telegraph line is down. Writing isolation in western horror means making it structural and specific: the protagonist cannot simply leave, cannot simply call for help, cannot simply wait it out, because the geography and the period will not allow it. Isolation in the western is not a temporary inconvenience but a permanent condition of frontier life, and the horror of the setting comes from understanding that this is what the setting actually was. People died out there and nobody found them for months.