If your trunk rattles because of bass its probably just the latch rattling and that can be fixed . If you go your local body shop and tell them the problem they will most likely be able to help you.
If you want to further rid your vehicle of vibration buy a some dynamat products
get some sound deading material and line the interior of your car as well as your trunk w/ it...a good alternative to dynomat is at http://www.sounddeadingmaterial.com
Take the system out of your trunk and put it in your passenger seat, then you won't even hear any rattles. In fact you won't hear anything for a long time.