So I've asked Manuel Reimer to create a referrer spoofer widget, and kindly he created it with PrefBar 3.4.1. Thank you Manuel!
To activate referrer spoofing in your PrefBar toolbar install or update Prefbar to 3.4.1, then download the Referer Spoof Menulist 1.0, click "Customize" on the toolbar and import the file. Then click on "Edit" to add all the referrer URLs you need for testing purposes, and enjoy. It works great.
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