What is the author's style in The Dog of the South by Charles Portis?

Ray Midge is a college student and former employee of a local newspaper. As such, his use of language must be relatively sophisticated, if the story is to have credibility. Becaue the other major characters are educated as well, they also must use appropriate English and do so throughout the work. The language alters markedly for characters who are of Mexican and Central American descent, however, as their English must necessarily be basic and somewhat grammatically challenged.