You don't need to collect everything; can just use unique landing pages, log a hit, and for signup include a specific campaign key (like "hn-spam-upvoted-190530

You don't need to collect everything; can just use unique landing pages, log a hit, and for signup include a specific campaign key (like "hn-spam-upvoted-190530") in the <form> and you more or less get a funnel without massive dragnets.