The typesetter for the 1905 LDS edition accidentally misread our as out. And this typo was subsequently copied into the 1911 LDS edition. Ultimately, the typo was removed from the text in the 1920 LDS edition. There is, of course, no such thing here as “pitching out tents”. Elsewhere the text has nine instances of “pitch our tents”.
Summary: Maintain the possessive pronoun our in Mormon 6:4: “we did pitch our tents” (the reading of the earliest text).