I don't think that Stephen necessary talked about advertise his subnet over public BGP.
There is the option to provide one or mode tunnels to other AMPR locations and use BGP to get the AMPR routes instead of IPIP/RIPv2. This is of course feasible, and it works nicely, and is how the entire European Hamnet works. There is a central tunneling point which provides global AMPR access, while all Hamnet paricipants use private BGP AS to maintain their routes, including the external ones.
This could be of course easily duplicated. But please use 32bit AS to prevent future collisions: http://laru.lu/on-the-air/hamnet-44net.html
Marius, YO2LOJ