That pretty much covers it, amigo Tom!
Regarding the Minnesota Clay moniker...they could have called him Boston Bob or Philapdelphia Frank and gotten the same results! Heh heh!
However, regarding the geography....there are a few SW's that have more geographical accuracy than a lot of American Westerns.
But, then again...there are some glarring examples of inaccuracy in SW's such as the map that Tony Anthony uses in BLINDMAN clearly shows Oklahoma which wasn't known as Oklahoma until much later. A lot of Maps in SW's are 20th Century maps showing Oklahoma as a State when in the period that the film is supposed to be taking place the maps would have read Indian Territory, instead. But, to be honest, you see this kind of stuff in a lot of American Westerns of the 40's and 50's, too.
And the same goes for weaponry, the Italians weren't the only ones to get the wrong guns for the wrong time period. Hollywood used to love to give Civil War era gunmen 1873 model Colt 45's, all the time!
But, you are dead on regarding the misspellings, the badges, and the Plains Indians outfits worn by actors that are supposed to be Navajos or Apaches.