This paper analyzes the design implications for space missions participating in opportunistic satellite federations. Satellite federations are a novel instance of distributed satellite systems implementing the concept of opportunistic collaboration in space among heterogeneous missions; trading resources, such as data relay; storage; and computing power among participant missions. The ability of a spacecraft to join a federation is mainly constrained by bus power availability and spacecraft attitude. The paper quantifies design implications for missions to participate in satellite federations. In particular, the paper quantifies the overall spacecraft mass impacts associated with operations on margins within a federation. A systems-level spacecraft model is developed to show that overall system mass impacts for typical-use low-Earth-orbit spacecraft participating in a satellite federation are 12, 1.1, and 0.6% for small-, medium-, and large-class platforms, respectively. It is shown that up to 500 s-1 per orbit federated satellite system connectivity is achievable for more then 70% lifetime on low-Earth-orbit platforms. The paper also addresses orbital geometry considerations by formulating a satellite-to-satellite coverage-optimization problem. This research work allows designers to identify optimal federation engagement levels for different satellite missions and helps to identify beneficial orbital geometries for federates seeking to act as resource suppliers.