His parents were married in 1876, at least three years before his birth. The earliest census I can find him on is
"Kansas State Census, 1895", database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QL8J-TZ7G : 11 November 2017), E M Lantz in entry for S P Lantz, 1895.
His WW I draft card gives his date of birth as 3 Dec 1879:
"United States World War I Draft Registration Cards, 1917-1918," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:K66V-Q4J : 13 March 2018), Elbert Michel Lantz, 1917-1918; citing Salina County, Kansas, United States, NARA microfilm publication M1509 (Washington D.C.: National Archives and Records Administration, n.d.); FHL microfilm 1,643,837.
I don't see any records naming him Arbogast. For someone born in 1879, a birth record might not exist. Given the social conventions then and now, I think the odds are overwhelming that he was born Lantz. In my opinion, you would need bulletproof documentation to use any LNAB other than Lantz. Happy hunting, and good luck!