Drupal - Ubercart customer pays % of order at Checkout

I need an experienced php/drupal developer. Site using Drupal 7. I need customers to have the option to pay only a percentage of the order total at checkout using Ubercart. The percentage needs to be pre-defined by admin. The data (amount paid, amount remaining) must be available to the Views module. I will need to be able to invoice the customer for the remaining amount but this does not have to be automated - I just need to have the functionality. Please no timewasters - This [project will require a custom module, if you dont have the skills and experience to complete the project, don't contact me. Due to recent experience, I will not release any payment until I see that work has started. You need to keep me informed regularly of progress. I will release 1/3 of the payment once I can see work is in progress. I will release the other 2/3 on completion. Please apply stating your experience, skills, and how you plan to implement the project.