Too hasty there.
As the paper is in the middle of a bond book, probably the 1972 volume of the El Paso Tribune, FaFDM is set no earlier than in 1973, after the said decision. So Clint could be a little cocky taking the sheriff’s star earlier on in the film; since killing the Morton brothers in Red Hull, Montana (they were Hank, Jim and Red Morton by the way) he had recived some law enforcement authority himself.
Cannot help you with the incident in Tucumcari, except it might involve two bandidos.
As for San Antonio, the story reads something like “two men whose name nobody knows arrived in San Antonio a few days ago and stopped in front of the old church. They were driving an old wagon … and appeared to be very tired … without saying a word to anybody, they … and drove the carriage … the old mission …”