Upload Folder (WebDav) allow upload (write) but not (read)

Question

I'm trying to setup my WebDAV server on Mac ML (apache 2.2) to allow an anonymous user to upload files but not see or be able to alter them once uploaded.

I know about the permissions on the folder (write only [drop box]) but my confusion is how to get this to work. Apache uses _www (user) and _www (group) so the owner becomes _www when a file is uploaded. setting group permissions to write only is not the solution.

drwx-wx-wx  24 _www  _www    816 Mar 18  2013 Upload

these permissions still allow seeing the files and it seems that apache needs to read files after they are uploaded?