This study builds upon previous work on single-layer invasion percolation in thin layers to incorporate a second layer with significantly different pore sizes and to study the impact of the resulting water configuration on gas-phase mass transport. We consider a situation where liquid water is injected at the assembly inlet through a series of independent injection points. The challenge is to ensure the transport of the liquid water while maintaining a good diffusive transport within the gas phase. The beneficial impact of the fine layer on the gas diffusion transport is shown. It is further shown that there exists a narrow range of fine layer thicknesses optimizing the gas transport. The results are discussed in relation with the water management issue in polymer electrolyte membrane fuel cells. Additional discussions, of more general interest in the context of thin porous system, are also offered.