Boot/Tailight seal

Hi all,

Purchased a 22 reg  superb hatchback last year. Had a nightmare with a leaky windscreen which was rectified. However I've noticed that my rear windscreen is extremely prone to steaming up, interior of the car is bone dry, no water in the spare wheel well or any wet carpet and or headlining. However I did notice the plastic trim and rubber in the boot gutter area was incorrectly fitted and so there was a gap which water would of been free to flow down (see picture). I've since refitted this and the rubber seal sits nice and flush. But I was curious where that water would have gone?? As I say the boot interior is bone dry, but I'm thinking there's water somewhere that's causing it to steam up still even after sorting out the seal (or there's another issue). Would I be needing to remove the side panels inside the boot to gain access and therefore dry out any water that may be in there, and if so how does that panel come out?

Any help appreciated.