How to create an alternative User ID (ie 14200260) in Drupal/Ubercart Store Affiliate system

Question

I want to offer users a unique Affiliate ID code that can be used to promote their marketing efforts in the form of a number generated when they signup or register on any of my Drupal project sites. At them moment, Ubercart (UC) Affiliate as far as I can see only shows the Users Affiliate Id number as their UID (i.e /site/affiliate/user/47 or similar).

My reason being is that an Affiliate User can 'introduce' new businesses by telling them to 'type in my code' in a search box then the system will take them to a 'list of Ubercart' offers which is related to that Affiliate user. So in the 'real world' sense a member could put a card in a shop window (write their number on it in pen; ie 142357) and later a 'reader' of the said card could enter such a code number into their device browser for enhanced sales benefits and the UC system track the affiliate as per the user type of backend system. At the moment, the current UC UID structure isn't that workable for my requirements.

I would like to be able to do this with Rules at the User site Sign-up stage and have a code set in a Profile type.

Does anyone have any ideas on how this could be achieved? From a marketing promotional perspective, I think this has lots of value to a marketing/sales dept (speaking as an ex-business college lecturer). (-: