You may have seen <A target="_blank" HREF=http://www.west.net/~lpm/hobie/archives/v1-i2/humor.shtml>this</A> before, but what a great project for winter...
I think the heat signature from an over full holding tank could be a problem. Remember the scene in Hunt for the Red October where the Baddies turned off all the safeties on their torpedoes and ended up shooting themselves?
I had an awful vision when I read your Subject _ PCWs! Those were the initials of the old Amstrad PC Wordprocessor of deep and painful memory. How relieved I was to discover that you had made a typo for PWCs, although both deserve the same final solution.