Still won't work. The Standard explicitly specifies that FILE type includes all stream attributes, including position indicator:

    ISO/IEC 9899:TC3 7.19.1 
    FILE
    which is an object type capable of recording all the information needed to control a
    stream, including its file position indicator, a pointer to its associated buffer (if any), an
    error indicator that records whether a read/write error has occurred, and an end-of-file
    indicator that records whether the end of the file has been reached;

Hence no stream can be longer than 2^(sizeof(FILE)*CHAR_BIT) (6.2.6.1 guarantees that objects of any type cannot have "hidden" bits of state not accounted by sizeof()).