uc_recurring does not store any credit card details, it works with gateways that provide existing recurring payment methods.

Although at its core uc_recurring is just designed to just triggers new orders at regular intervals which is why its perfectly suitable for a payment plan. The idea of paying for an order after receiving an invoice is really just a different payment method and would be a useful addition to ubercart by itself. uc_recurring could certainly be altered to work with this invoice payment method.