I'm researching Pagel lines, not Kieper, but this may help you a little more.I think the USA church records would be the greatest help to you right now. They may even give the town they were from in Europe.
This appears to be Hermanin the 1880 census. There are no other Kieper in WI at that time.
Census Place: Oshkosh, Winnebago, Wisconsin Source: FHL Film 1255453National Archives Film T9-1453Page 153B Relation Sex Marr Race Age Birthplace Robert SMALL Self M M W 41 ENG Occ: Farmer Fa: ENG Mo: IRE Elizabeth SMALL Wife F M W 35 WI Occ: Keeping House Fa: ENG Mo: IRE Cathrine SMALL Dau F S W 13 WI Occ: School Fa: ENG Mo: WI Mabel F. SMALL Dau F S W 10 WI Occ: School Fa: ENG Mo: WI Mary H. SMALL Dau F S W 6 WI Occ: School Fa: ENG Mo: WI Lanara B. SMALL Dau F S W 4 WI Fa: ENG Mo: WI Elmer B. SMALL Son M S W 2 WI Fa: ENG Mo: WI Herman A. KIEPER Other M S W 21 PRUS Occ: Farm Laborer Fa: PRUS Mo: PRUS