I have checked into many sources and the only item I can find is at St John's Luth Cemetery (38th and Good Hope, Milwaukee). There is a Johann HEUER buried at this cemetery.
He *may* still be buried where his wife is - perhaps the marker deteriorated. Do you know where the Petermanns are buried? Could he be there? You might want to check with Union Cemetery and Lincoln Memorial (formerly Wanderer's Rest) in Milwaukee. MANY German immigrants are buried there.
I am not sure what you are referring to when you say Oz courthouse records 'don't go back far enough'. Vital stats there go back to the late 1840's/early 1850's. Not every B-M-D was recorded since it was not legislated by law.
Area churches were usually better at maintaining vital stats of their members, however that was dependant upon the minister. Some very good at record keeping, others were not. Some did not even record ANY - those are the ones you hope never apply to your ancestor hunt (grin). Good Luck.