The technical evolution enables the development and application of autonomous systems in various domains. In the on-road and off-road vehicle domains, autonomous vehicles are applied in different contexts. Autonomous cars are designed as single system solutions, while in other scenarios, multiple autonomous or semi-autonomous vehicles are integrated into a system-of-systems. We utilize a case from the earth-moving machinery domain, where a fleet of autonomous vehicles is used for transporting material in off-road environments. The traditional industrial development processes in the earth-moving machinery domain focus on single human-operated systems and lack clear support for autonomous system-of-systems. From our studies of industrial development of system-of-systems, we recognize the demand for guidance on how to document a system-of-systems. The goal of this work is to provide a framework using different model-based formalisms. As a structural background, we utilize the SafeSoS process, where each step specifies details about the targeted system-of-systems. Specifically, we apply model-based systems engineering to describe the structure and behavior of each SoS level. We utilize an industrial case to exemplify how model-based concepts can be applied to capture relevant information needed for designing the system-of-systems. This work provides guidelines for practitioners in developing safe system-of-systems.