This is crazy, I agree.

Typically, in situations like this, I employ an "original_file_name.info" file instead.

In the .info file I'll put all the information necessary for another program/user
to verify the contents of the huge file i created.

There are other options . . . . like creating a dummy header record in
the file creation program . . . and then using fseek() to hop back to
the beginning and overwrite the header info....

but you may not have this much control over how this file is created.