In mobile ad hoc networks, nodes interact peer-to-peer. They self-organize, share workloads and provide services that they also use. There are middleware platforms, designed for the Internet, which support the development of peer-to-peer distributed systems, providing an interface for subject-based data routing. These platforms put emphasis on decentralization and resilience, and guarantee bounded lookup costs. Hence, we consider these platforms appealing for ad hoc environments. In this paper, we show how a cross-layer protocol stack design for ad hoc nodes, simplifies the tasks of a subject-based routing substrate in ad hoc environments. We give details for a platform like Pastry, emphasizing the cross-layer interaction with a pro-active routing protocol at the network layer.