Ironically enough, the one Clanton that survived the gunfight would probably not have been mourned at all if he had been the only one killed. Ike Clanton was the primary instigator of all of it, but Wyatt did sort of screw him over before things went to shit.
Pretty much, be an earlier version of the Bisbee Massacre. All of the Cowboys would have to leave Arizona. The Earps weren't the most popular people in Cochise County, but they had the law on their side. Citizens would have taken justice in their own hands if the Earps had been killed.
Utah or Pah-Ute, or even Goshute, could work.
I'd swap Rio Grande for New Mexico and New Mexico for Dinetah since you've got the Rio Grande boundary, but that's me. I started reading your TL today, nice job.
Beautiful map, but one question: were the Navajo or Apache moved to OTL Utah/Nevada? Because the Dinetah depicted here was the traditional lands of the Paiute, Ute, and Utah.
You've got the Hopi Reservation and the western half of the Navajo Nation in the same district (21st) as Flagstaff and heavily GOG Kingman and Mojave County, but if it's 90% Navajo then it can't possibly be a safe R district. Something's off there.
Respectfully, the Navajo, Apache, and Hopi...