In the realm of nuclear security, the prevalent use of large and costly fixed radiation portal monitors for inspecting maritime shipping container cargo poses limitations on widespread deployment. This study emphasizes the optimization of informed paths using an innovative mobile radiation detection system designed for security and defense applications. The gamma-ray detection system incorporates a compact and cost-effective plastic scintillator with silicon photomultiplier readout, enabling integration into weight-restricted platforms like multirotors. Using a real-time gamma-ray source search algorithm, based on a maximum likelihood estimation, it is possible to estimate the source position coordinates while the detection system performs a container perimeter scan. Informative path planning based on two profit functions, which account for the gamma-ray counts and background, was analyzed and compared with predefined paths. Simulations with a \(^{137}{\text {Cs}}\) gamma-ray source inside a shipping container demonstrate improved source position accuracy when using informed paths ultimately reducing the inspection time.