The NRT is an international collaboration to design and build a leading astronomical facility in the optical and near infrared ranges for the emergent area of time domain astronomy. That relies on the combination of a large collecting area (4 m diameter), quick response (<30 s), and full robotic operation. The system level analysis and trade-offs for assessing image quality, defining optics and optomechanics requirements, integration of both, and expected performance are particular challenging issues for such segmented optical configuration. This contribution presents the methodology developed within the project to produce suitable optical and optomechanical models and measure their performance. This methodology optimizes system level parameter exploration and tradeoffs, quick regeneration of models after possible changes in the design, and integration between optical and mechanical analysis.