Thanks for the input, Bro. Water collects inside right rear cargo area, below the little stow compartment, even when the car is parked - which makes me think it isn't being pushed into the area by air pressure or splashed up by tires. (Unless it's being splashed in and then draining slowly, hmmmm.)
The inside of the stow compartment is wet. I've noticed drops of water under the window seal above the stow compartment. I'll get it figured out soon or buy a new one - I've kind of been looking for a reason to get another Legacy GT wagon.
BTW - I'd read the TSB on the map light drip. I don't think it applies here but it's good to be reminded that my situation could be a lot worse!