Multifunctional structural materials capable of simultaneously absorbing electromagnetic waves and bearing mechanical loads offer important advantages in aerospace applications, including lightweight construction, compact design, and integrated performance. The design of the unit cell is essential for enhancing such integrated performance. In this work, A sensitivity-based topology optimization framework is developed to design unit cells for these multifunctional materials. Within the proposed framework, the material distribution is described by a continuous density field based on the SIMP model. Electromagnetic wave absorption performance is evaluated using the Rigorous Coupled-Wave Analysis method, and the corresponding analytical sensitivities are derived. The equivalent elastic modulus of the structure is computed via the energy-based homogenization approach. A scalarized objective function is formulated using compromise programming, combining metrics for broadband absorption and mechanical rigidity. The resulting optimization problem is solved iteratively using the Method of Moving Asymptotes. Following optimization, a final design is reconstructed. Its performance is then further enhanced via sensitivity-driven parametric optimization of key characteristic dimensions. Numerical examples illustrate how the weighting coefficients determine the relative importance of each physical field, thereby explicitly controlling performance trade-offs. Due to its rapid convergence, this optimization framework offers a viable pathway for designing lightweight, load-bearing stealth components for future aerospace systems.