We're in the process of transitioning
packages.ros.org hosting from Willow to OSU OSL. When we make that transition they do have a couple of locations where they are mirrored.
For location specific mirrors we'd need someone who could donate a lot of bandwidth and work with us to make sure that the mirrors stay current.
For mirroring with a fallback on a local network, I would recommend just using squid. We use it on our build machines which repeatedly redownload packages and it makes a huge difference.
Tully