Hi all,
I've just cured a couple of issues behind the two side boot trims which were causing significant water to build up under the boot carpet which then tracks forward beneath the water proof carpet backing.
1- roof rail / sun roof drains run down a tube in side the C pillars rearward of the two back doors. They connect to a rubber boot which goes through the wing above the rear wheel, and drop out behind the ends of the rear bumper. The hose to boot connection was away dropping the water on the floor inside the vehicle! Reconnected and fitted cable tie to hold in place. You get to the hose by removing the boot area side trim panels.
2- near side rear quarter, behind boot side trim panel, panel joint between metal inner wing, and lower floor panel, and inner metal wheel arch (just below and behind the ns rear light cluster) - panel joint not sealed. Rain falling on nsr rear window running behind bumper, then flooding the area behind the light cluster to several inches deep!!! From there it floods over onto the rear boot floor pan under the carpets, and tracks everywhere!!!! Reasealed panel joint after cleaning / drying, and punched small hole in grommet at base of flood area behind nsr light. Result - no more condensation!!! So far.......
Might not be the solution in your case, but you can add these to the many possibles!!!
Cheers and good luck