And it turns out that Mecklenburg-Schwerin (which is the state in which Steffenshagen was then located) is one of the few German states to have preserved census records from the 19th century.
So here is the 1867 census for the Lange family in Nieder-Steffenshagen (then located in the "Domanialamt", equivalent to a county, of Doberan): https://www.ancestry.com/sharing/21076171?h=743628&utm_campaign=bandido-webparts&utm_source=post-share-modal&utm_medium=copy-url
It shows Johann Lange, born 1812, as head of household, with occupation shoe-repairer (Altschuster); wife Carlina [sic], born 1829, and their children Sophi [sic - probably Sophie] (born 1853), Marie (born 1855), Johann (born 1858), Ludwig (born 1864), and Louise (born 1866). They are all marked as being Lutherans, subjects of Mecklenburg-Schwerin, and permanent members of the household (that is, not just visiting on the day of the census, which was 3 December 1867).