Gringo in the meaning we think of it today is a Mexican term. Also, your wife is fine with it? Spanish people seem to often be rude about people speaking Mexican Spanish.
I worked for years with a guy from New Mexico whose many times great grandfather came to the area with the expedition of Peralta, and settled an area near Sante Fe that had the only water for many miles.
He spoke Castilian Spanish, as did his remote ancestor, and could barely understand Mexicans. He said he was welcomed with open arms when he visited Spain in the 1970’s while in the USAF.