Correct me if I am wrong...but cant you use an ER product and stack the IP's on one port, then NAT between the subnets? I did thes from a single station private IP on a customers house, then to 3 different customers via buried line as they were all close to each other. So from the multi 10.60.x.x (eth 1) to multi different 192.x.x.x respectively on 2,3,4.
Wouldnt this be allowed on the public domain as well? Each "user" would get an address then NAT to eth 0 (lets say) and out to the net?