Local Fort Atkinson area papers might be found at NewspaperARCHIVE.com
Check with a local library for institutional access.
Adverts in early Milwaukee papers would be found through:
"19th Century U.S. Newspapers" (Gale)
- or -
"America's Obituaries & Death Notices" (NewsBank.com; searchable full editions through mpl.org)
Haubert family in the old Town of Lake (Milwaukee County) are found in "Milwaukee's German Newspapers; an index of death notices and related items" (1844-1950). Celebrating 10 years!https://encore.mcfls.org/iii/encore/record/C__Rb3327521
Related surnames are Seymer Gutmann Denker Rust Bergs - Hauber & Häuber names are also found in the index connected with surnames like Zimmerlin Maier Spindler.