Ideas for my back panel ('94) anyone??

My back panel on my corolla by the break light rattles like there is no tomorrow since I installed my system. I had a lot of rattling in my trunk but I fixed that by putting some old fabric in between the trunk and the bars.
I was thinking of maybe doing a similar thing with the panel. I also was thinking I could take it out and put somehting else there instead. Maybe some kind of wiring so that the sound can come throught better too.