Network 1 Topology is designed so that Routing networks communicate with Routing networks, and Stealth networks communicate with Stealth networks (that is, host A [Stealth] cannot talk to host B [Router]).
NAT works in Stealth networks only, since Routing networks are not able to NAT through a Stealth network (that is, not able to NAT host A to talk to host B).
Proxies cannot be used from the Stealth networks to the Stealth networks.