Isogeometric Analysis (IGA) has emerged as a powerful framework for the shape optimization of thin shell structures by unifying geometric design and structural analysis. However, a significant challenge remains in generating analysis-suitable spline parameterizations for complex geometries, where standard mapping techniques often result in distorted control grids. This work proposes an integrated workflow that combines advanced adaptive fitting with isogeometric shell optimization to overcome these limitations. The initial geometry is obtained using an iterative re-parameterization method based on a plane-stress analogy, as described by Marini´c-Kragi´c and Vuˇcina [1]. This approach ensures high-quality element distribution and enables the representation of complex topologies using a single-patch B-spline surface. By solving for a relaxation field that minimizes metric distortion, the method redistributes control points to capture intricate geometric features while maintaining a smooth and regular grid suitable for analysis. Subsequently, the generated single-patch surface is utilized for isogeometric shape optimization, following a gradient-based approach similar to the work of Bandara and Cirak [2]. The high quality of the initial parameterization significantly enhances the robustness of the optimization process and the accuracy of the Kirchhoff-Love shell elements. Numerical results demonstrate that the proposed method effectively achieves superior geometric fidelity and structural performance, even for complex shell designs, within a unified single-patch framework.