It sounds like you found your leak source. Congrats. I had a leak that caused the carpet in the rear of my 16' Casita
SD, rear dinette area, to get soaked. We ended up tearing the whole backend of trailer up searching for the leak. We finally discovered the water was coming in the rear brake light
fixture and leaking inside, down the wall and pooling near the table. No wet walls at all. I write this to let you know if the tiny little gaskets on any of your lenses on your lights
rots or falls out, it could allow water inside. We pulled the red lens cover off and could see water had pooled up, then drained into the trailer. Who knew?? Keep it in mind for the future. Maybe it will save you some time and a mess in the future.