I got 2 15's in my trunk with my backseat folded down, attempting to do a wall just in my trunk. I have only a few inches of gap on each side of the box I want to seal off from the trunk hoping to gain a little bit more on the meter. I used to compact towels and stuff in the cracks but it don't look that great and I doubt if it works haha. How can I seal it off correctly. Any suggestions?