This extended abstract reports on steps towards an environment for repeatable and scalable experiments on wide-area cyber-physical systems. The cyber-physical systems that underlie the world's critical infrastructure are increasingly vulnerable to attack and failure. Our work has focused on secure and resilient communication technology for the electric power grid, a subset of the general cyber-physical problem. We have demonstrated tools and methodology for experimentation with GridStat, a middleware system designed to provide enhanced communication service for the grid, within the DETERlab cyber-security testbed. Experiment design tools for DETERlab and for GridStat will ease the creation and execution of relatively large experiments, and they should make this environment accessible to users inexperienced with cluster testbeds. This abstract presents brief overviews of DETERLab and of GridStat and describes their integration. It also describes a large scale GridStat/DETERlab experiment.