I am glad to know that we at least found your great grandfather's resting place. I was planning on photographing headstones in the Peoples Township Cemetery and David Peoples Cemetery today. They are both located in Boone County just above the Boone/Dallas county line. There are a lot of Hansens buried in the Peoples Township Cemetery that are mis-identified on find a grave as being buried in David Peoples. Hopefully I will find the Peter you are looking for. I realized last night that the Peter I thought your ggrandfather stayed with didn't come from Germany until 1883, so he could not be the one Christian stayed with. I also realized that the battery for the camera I borrowed doesn't hold a charge, so I didn't make it out to any cemeteries today. I will keep looking for the Peter you are looking for, though.
Some towns I have found that Hansens have come from in Schleswig-Holstein are Tolk, Brodersby and Neuberand. According to google maps, it is 34km from Brodersby to Tolk and 11km from Tolk to Neuberand, so I would assume that they are all related in some way, I have just hit a dead end when it comes to tracing the families back to Germany.