There's a death certificate for a Daniel Boughner on Ancestry. It states that he died in Middlesex, Ontario, Canada, in 1924 at the age of 77 (which would put his birthdate in 1847, not 1866 as I had thought). It also lists his parents as Sidney Boughner and ?? Bolby, and I have his parents listed as William Boughner and Lois Walker, so this may not be the same person, but Middlesex is right around Elgin, where Roy was born in 1893.
Archives of Ontario. Registrations of Deaths, 1869-1938 (MS 935, reels 1-615), 1943-1945. Archives of Ontario, Toronto, Ontario, Canada.Archives of Ontario. Registrations of Ontario Overseas Deaths, 1939-1947. MS 944, reels 1-11. Archives of Ontario, Toronto, Ontario, Canada.Archives of Ontario. Division Registrar Vital Statistics Records, 1858-1930. MS 940, reels 5-10, 16, 21, 26-27. Archives of Ontario, Toronto, Ontario, Canada.