If we did BGP over IPIP would that work? Are you able to run Quagga or something that can do BGP/Routemaps on your FreeBSD box? What version of FreeBSD is it?
Is the CAIDA telescope a external system? Perhaps a SHIM box with quagga & GRE Tunnels between CAIDA & amprgw?
Tim Osburn www.osburn.com 206.812.6214 W7RSZ
Updated drawing: https://www.osburn.com/amprnet-150614-1.1.1-bgptunnels.jpg
Tim Osburn www.osburn.com W7RSZ