I had a water leak "near" the door area, coming down from some area near/at the roof, and after quite a bit of eliminating possible sources, it turned out that the amber colored running lights on the front had become loose, and in rain events, and especially travel during rain, the water going in at the gap of the light cover, at the housing, and was tracking back a ways, and then to a vertical internal rib, and running down next to the door.
Just a possibility!
Good luck finding/fixing the problem!
The FunderStream rehab is complete, and we are hitting the highway!
1998 Excella 28'
2008 Toyota Tundra 5.7L with HAHA