A description for flutter and dynamic loads prediction is laid out based on state-space systems around a nonlinear equilibrium. In order to reduce the computational times associated with building and manipulating these systems, a newmethodology is proposed to build parametric reduced-order models of the unsteady aerodynamic systems from optimal Latin-Hypercube design of experiments, frequency-limited balancing techniques and interpolation on the transfer functions of the resulting reduced systems. Optimization of the kernels encapsulating the parametric dependence is also studied. The developed tools are employed for the aeroelastic design optimization of a very flexible strut-braced wing with flutter constraints. Results show a promising approach to be deployed in design problems where dynamics and stability are to be included in the analysis and geometrically nonlinear effects are to be accounted for.