Hi Michael,
Thanks for reaching out!
While a waitlist feature is something we are considering, it is not currently a feature that is available out of the box – sorry for the bad news there! However, you can use Event Tickets (which has the RSVP functionality) in conjunction with Event Tickets Plus to set up something similar on your site.
It sounds like the simplest way to do this for your use case would be to simply create two tickets, one being the “real” ticket/RSVP with a limited stock, and one (RSVP) called “Waitlist” or something similar. This way, if users see the main ticket is sold out, they can still sign up for the waitlist ticket.
If you want to hide/disable the waitlist ticket until the main ticket is sold out, you could do this with a customization. For this, our themer’s guide is the place to start! We also have a list of recommended developers if you’d like to get some help with the code.
I’d also recommend casting your vote for this feature over in our Feature Ideas Forum, which is what we use to gauge user interest in new features and help guide future development efforts.
I’m sorry I don’t have a more straight-forward solution for you here, but I hope this helps! Please let me know if you have any questions, or if you get stuck with the customization – I’ll be happy to point you in the right direction!
Thanks,
Jennifer