We present a methodology for the simulation of next-generation Augmented Reality (AR) User Interfaces (UIs) within immersive Virtual Reality (VR). We use a user-centered model to support design decisions for specialized operations in high stakes fields, and present augmented reality user interface designs for two use cases in public safety: a law enforcement traffic stop and a firefighting search and rescue scenario. By utilizing VR to simulate AR, we can design and evaluate the benefits of idealized UIs that are unencumbered by hardware limitations. We discuss the trade-offs of Virtual Reality as a medium for simulation and training of next-generation Augmented Reality User Interfaces.