Hi Dominic!
Thanks for getting in touch! 🙂
First off, I do want to note that we are fairly limited in how much we can support custom development questions like this.
That said, I’d be happy to at least point you in the right direction as best I can.
You can achieve that by making a template customization of the rsvp.php template file located at /wp-content/plugins/event-tickets/src/views/tickets/. You should check our themer’s guide to see how you can accomplish that.
I hope that helps! Let me know if you have other questions and I’ll be happy to help.
Cheers!
Victor