Hi Courtney,
WooCommerce Tickets does support SKUs for products. So while it might be messy, I believe it could do it. You could list an event – such as a test date – and then add 20 ticket types, each with it’s own SKU and a quantity of (1). Unsold codes, which are “products” to WooCommerce, would have to be deleted since they are associated with an event, but you could certainly reuse the SKU for future events. The only other thing I should mention is that on the event page, 20 tickets would be listed there, and of course they would only have to select one.
I also think that WooCommerce Tickets could be customized to be a more elegant solution for you, if you wanted to go that route.
Does that make sense? Please let me know if there’s anything else I can help you with.
— Julie