Rotating banner in header of all sites in network

I am wondering what would be the best way to insert a rotating banner into the header of the super admin site and have the same banner duplicated to all sites created through multi site.

We are using multi site to basically create cloned websites of the master for affiliates and partners so they can use them for promotion. Part of the design we have mocked up has a rotating banner in the header that will cycle through a set of roughly 4 images with different messages. As we want to basically clone the exact layout and design out on all the affiliate sites, we would like the same banner rotated on all of them.

Any ideas on the best way to do this?