Write custom code for Marketo marketing automation platform

My company uses 'Marketo' for all our marketing automation, in particular, outbound event invites. We use 'Splash That' as the registration page for these events. We rely heavily on the event registration functionalities that Splash provides but lately the platform itself has been unreliable. All event invitations are currently sent out through Marketo and we have been wanting to make the switch for the registration portion for a while now. Unfortunately the standard functionalities that Marketo offers will not cut it and we will need to incorporate some custom coding. Here is a list/description of the features we want coded into our Marketo instance: • Access Codes - Only people invited can register (With Splash we upload the send list and people cannot access the registration page without typing in one of the email addresses on that send list) o Each email address can be used just once (To prevent the sharing of access codes) o This will need to work for not only emails sent from Marketo, but emails our account reps are sending out personally. (We currently add these lists to splash as well) • Waitlist – To not only cap the number of people who can register, but to place all additional RSVPs on a “Waitlist” o Automatically add people to the waitlist when we have reached the RSVP cap o Moved people from the Waitlist to the RSVP list if someone cancels their reservation(This would need to trigger an automated email letting people know they are now off the waitlist for that event) • RSVP Cancellation feature o A feature that lives within the registration confirmation email that allows people to cancel for a particular program Please keep in mind that Marketo is synced with our Salesforce instance. Also, we do not want to incorporate Splash That into the coding. The purpose of this solution is to completely replace that with a custom solution in Marketo.