Stripping out the trunk - water leakage

Hi All -

TL;DR - Looking for instructions / guide / YT video about how to take off the interior trim in the trunk (and then be able to put it back together later).

The Long Version -- Have water coming into the trunk on rainy days. Took it to the dealer and they checked the usual suspects, cleared drainage tunnels, etc and were like... "yeah, idk". And suggested I go to a body shop. Took it to a body shop and they are like "its' gonna cost $$$ just to troubleshoot this". After a lot of watching (and mopping) on rainy days I've basically narrowed down that it comes in from the sides. If I take out the trunk floor and the foam pieces and then stick my fingers under the side trim - that's clearly where the water is. Both sides, too - although more so on the left. So I am looking to remove the side trim and hit her with a garden hose to see what the culprit is.

Could be a coincidence but shortly before I started seeing the water, I replaced the plastic rear quarter panel doodads on the C pillars. We had a stretch of dry weather for a few weeks at that time so no big deal. But then the rains started and yeah, it's all been downhill from there. So that's my theory.