Nismo rattle over bumps (culprit - rear bumper!) video embedded..need advice on a fix

[Koz1614]

Fellas,

After tearing apart my whole trunk and carefully poking around I have found the source of the rattle that I hear coming from the rear passenger side of the hatch when going over bumps. The problem is where the rear bumper meets the driver side quarter panel over the wheel well. If you press along that seam you get a terrible squeak/rattle that travels right through the hatch. Now the question is - Any suggestions how to fix this? Car is practically new with 2k miles on it, so I'm trying to keep from doing anything too invasive.

Sorry to repost but I really need some advice on a fix! I don't know where to begin with this one. The car is under warranty, but I would rather try and fix this myself.