Early electrical/electronic (E/E) architecture decisions in ground combat vehicles (GCVs) strongly influence lifecycle cost, upgradeability, survivability, cyber resilience, and integration risk across decades-long service lives. As Army programs transition from distributed E/E architectures toward zonal and software-defined vehicle concepts, the number of viable architectural options expands while the cost of late architectural change increases. This paper presents a detailed, model-based architecture evaluation methodology structured around Requirements–Functional–Logical–Physical (RFLP) principles, using Modular Open Systems Approach (MOSA) constraints as architectural requirements and VICTORY-aligned concepts as validation targets. The methodology emphasizes multi-variant architecture definition with large-scale reuse, early synthesis of wiring and network impacts, end-to-end traceability, change impact awareness, and continuity from architecture evaluation into detailed, multi-team design. The approach enables early, evidence-based comparison of architectural alternatives and preserves a traceable rationale to support modernization, sustainment, and future system evolution.