(Recommend just creating this on production since people aren't really going to see the landing page yet. It's kind of a pain to set up, it's probably easier to just set up and test on production.)
id of the ul is campaign-avatar-pickerdata-avatar-id needs to be set for each tag for each avatar. You can figure out the data-avatar-id by going to the Admin page of the avatar group, inspecting the source for the 'Delete' button, and finding the ID in the form action URL.