I "think" the door drains are just under the weatherstripping but it's been a long time so maybe someone else can chime in. Are you really really sure that the sunroof drains are OK ??
The vapour barrier is to keep water vapours from condensing in the door due to differences in temperature not to prevent leaks.

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)