I've been through that region (Encampment, Rawlins, Lander, Dubois). While there's obviously a large cowboy population, I don't think a kilt would completely blow people's minds. There are enough rock climbers in Lander who'd think a kilt is cool, and honestly I think anyone in Dubois wouldn't give you a hard time either. I've never been to Rock Springs so I can't speak for that community, but if it's the same vibe as what I mentioned it shouldn't be a problem.

Andrew.