I bought a book when I was in Bolivia called "Alemanes en el oriente boliviano" by Mario Gabriel Hollweg.A pilot by the name of Jorge Wilstermann (yes, in the book, the surname is spelled with a double 'n') is named on page 461 of the book.It does not have information about how/ when his ancestors arrived in Bolivia, but it does have information that you might not yet have. Here it is:
Jorge worked as a pilot for a company called "Lloyd Aereo Boliviano".
Jorge died January 17, 1936 en la region Tapacari, entre Cochabamba y Oruro. He died in a plane crash in which all occupants died.