Thanks guys. Sounds like the trough+drains might be part of the plan for condensation, but that's not the source I'm seeing.

Also, the clam to bottom seal looks good and the leak is above it.

I'm seeing water in the trough from a hose streaming water down the side of the trailer over the rub rail. Not sure if this part is supposed to leak or not.

I can try Cobra, but I though I'd ask here first.