If you are struggling with finding a particular person by name, zoom out and study the profession as a whole, for context. Think about how you might research land agents in Wisconsin, and gather context for how property was recorded and transferred in your period of study.
Pretend you are brand-new to the area, set aside previous research, and start fresh. How well do you know the place where your person of interest might have lived and worked?
Look at the FamilySearch Research Wiki's main article on Wisconsin Genealogy and the article on Land and Property. Review the process of how land was surveyed and transferred, and consider what records might have been created. If you haven't already, go to the Library of Congress and look at the historical land owner maps and atlases, and look for other historical maps from that period. Looking at the USGS's historical map collection can give you an idea of the terrain and how people might have travelled in and out of the area.
Rather than searching historical newspapers for a name, when you aren't sure what form it might take, search by keywords: "land" "agent" and other related words. Look for advertisements. Can you find the name of a land agent whose name is easier to search for? Look for them and note the newspapers and historical records, local histories, and other works where their name appears.
The more you can dive into local history, the more supporting information you'll have to inform your search for people. Be creative. Look at libraries and archives for research guides and finding aids, at the local, regional, and state level. Check both public libraries university libraries, historical societies, and genealogical societies.
One example: the Milwaukee Public Library has a guide to researching House History. What resources do they suggest? Do similar resources exist for your area of interest?
Look outside the websites which are designed for genealogists and see what projects have been done by other historians, such as Immigrant Entrepreneurship: German-American Business Biographies 1720 to the present.
Your land agent presumably sold land to people. Who were the customers? Study the people your agent would have dealt with and see if you can discover him via his associates and neighbors. Look at Naturalization records in the area; does he appear as a witness on declarations or petitions?
Did prominent landowners in the area leave letters and other papers in archives? Check ArchiveGrid, WorldCat, and NUCMC for manuscript collections, special collections, and research guides to those collections. If you have access to Findmypast, search PERSI, the Periodical Source Index, for your place of interest.
This kind of problem highlights how we are underserved by the large sites such as MyHeritage, Ancestry, and FamilySearch, who are dedicated to helping us find people by name. If we don't know how the name might be recorded in records, the whole system breaks down. At some point we have to leave the genealogy nest and take more creative steps to find the information we want. Flipping a research question on its head and looking at buyers instead of sellers, studying an industry rather than its workers, and learing about the community in general can be ways to broaden our perspective. We can learn much by studying the work of local historians, social historians, people doing population studies, and researchers in other related disciplines.
Keep a journal of what you find and write down your ideas, and continue to review what records and documents you've already found (or not found). Make notes about where you searched and how you searched. As you learn more about the history, you may get more clues from the records you've already found, because small details you overlooked before will gain more significance.
Above all, have fun! Researching for context can be a refeshing break from searching for people by name.
Final note: researchers who have a lot of research in Wisconsin should consider joining the Wisconsin State Genealogical Society. Take a look at their resources, some of which are free to the public, some of which are members-only. At the very least, keep an eye on their excellent webinar series; the initial broadcasts are open to the public.
