Sealing trunk/rear deck with retractable seat belts in the way

[Simonpiper]

As the title says I am stumped with how to seal off my rear deck as there are seat belts that go through the deck and the retractable bit has got me stumped as to how could seal it. Any tips? I will post pics shortly. 2010 vw Passat sedan

 

[crispy_chick3n]

give the retractors their own little "enclosure". kind of like a bowl or a box under them and then seal that enclosure to the bottom of the deck would be my best guess on how to do it. pictures would for sure help if you get around to posting them.