I have a copy of an 1860 census which shows a Louis Eckhardt from St. Louis age 14, living with a family.The mans name is Jacob Jargen age 40 a farmer from Switzerland and a young lady by the name of Mary Jargen age 21 born in Pennsylvania and of course Louis born in Gasconade County, Roark, Township, Missouri.
This info comes from the Missouri Census 1830-70.Page 488 Federal Population Schedule, Missouri 1860 Federal Census Index, ID# MO22932554.
I too was searching for my grandfather, but it turns out his name was Lewis Eckhardt and he was living in Illinois.
My e-mail address is JGiblin475@aol.com
Good luck and if I can help any further please e-mail me.