If you think that your storing addresses in Discourse is more dangerous than wherever else you’re storing them is a privacy concern, you’ll need to create them. If you don’t like the API, you could do it from rails:
i=Invite.generate(user, skip_email: true, max_redemptions_allowed: 1)
Gives you an invite key.
"/invites/#{i.invite_key}"
is the URL. You could do something to write them all to a file.