@rosyteddy
I looked at those, but they require multisites, which I’m not using currently. I suppose I could set it up, but I’m not sure I’m desperate enough since I don’t need any other multisite functionality.
Everything else in the linked conversation I’ve tried. They’re all pretty out of date and are either kinda finicky or just plain don’t work. Having fiddled around with it further, even WP-Invites doesn’t currently work.
I’m not sure that Invite-Anyone does what I need it to. I don’t see any option to lock down the site so that an invite is required to join. What I really want is a form on the registration page that asks for an invite code so that someone has to enter a valid invite code in order to join.
I’m sort of working around things right now with a “security question” on WangGuard that I’m using as a password instead (by setting up a question with a non-word, pretty much unguessable answer). Still, actual invite codes would be nice.