MUCH simpler idea - I think

htaccess checks the Query String, not the Referer.

IF (Query String != long_string_a+date+long_string_b+hour+long_string_
+c) THEN

     redirect to logging script on other server, appending the origina
+lly requested url, the local date and the local hour

ELSE
     simply re-write url to remove query string
END
[download]

The Perl script on the other server strips the originally requested url, date and hour, generates a Query String using static long_string_a, b, and c, the date and the hour, and redirects back to

originally_requested_url?q=long_string_a+date+long_string_b+hour+long_string_c

But htaccess strips the Query string off, so noone ever sees it, it's nigh impossible to guess, and it's dynamic so very hard to spoof.

Any holes in my theory?