Is set in Texas and Mexico
Not sure of how the story would unfold but there’s plenty of reference possibilities
Red Dead Redemption
All of these movies http://en.wikipedia.org/wiki/Category:Films_set_in_Texas
All of these movies http://en.wikipedia.org/wiki/Category:Films_set_in_Mexico
We all know how much Bethesda/ZeniMax love including external references in their games, especially in the two Fallout games they have released.
Heck you could play as the “Lone Ranger” even, if only by nickname (a la “The Courier”).
The use of South of the Border by Frank Sinatra as the opening theme.