I'm very happy to report that the problem is solved. Let me refer to this picture:
I found that the wet carpet at the bottom of the door was due to the seal of the door membrane being loose along the bottom edge of the door, to the left of the subwoofer module or rear of what I'd noted as wet. I re-sealed the entire bottom edge of the membrane with RTV Silicone Sealant and that seems to have cured the leak.