Incoming web traffic from various sources will visit SITE A, and then get automatically redirected to SITE B. The catch is that the headers will show the SITE A page as the referrer.
Occasional blank referrers are ok, as browsers may not always behave the same, however the goal is to change the referrer, not to blank it out (such as what a meta-refresh tends to do).
The user config (specifying the redirect location etc.) can be right in the script files, no GUI admin page is needed unless it makes sense to do it that way for some reason.