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To investigate the hydrodynamic performance of the floating platform VolturnUS-S as configured for the 1^st Floating Offshore Wind Turbine (FOWT) Comparative Study, we have used a Smoothed Particle Hydrodynamics (SPH) based solver that features a coupling to the cable dynamic solver MoorDyn+ to reproduce the proposed benchmarks. This is a quite novel application of the method to simulate semi-submersible platforms for offshore wind energy. For this benchmark, which does not include aerodynamic actions, we have proposed a new procedure, leveraging offline coupling techniques to model the problem in a sub-domain of the reference wave basin. Our approach is detailed and validated for wave propagation only, and thus applied to reproduce the wave-platform interaction for an extreme focused wave condition. Good results are obtained for the wave generation and validation using open boundary conditions as well as for the platform motion under the extreme event.