I don't think it's a good idea to use a strap-on rack on the tailgate, but YMMV.
I would recommend using Bill Davis' Quick Release hitch, and using a hitch-mount rack.
Video here: https://www.youtube.com/watch?v=wJbZgezZS_U&noredirect=1" onclick="window.open(this.href);return false;
MNL thread here: http://www.mynissanleaf.com/viewtopic.php?f=41&t=7829" onclick="window.open(this.href);return false;