Ported box and false wall

[SQMonte]

I want to do a ported box in my trunk with subs/port firing back but I also want to build a false wall to make it looks cleaner. I currently have no speakers in my rear deck so the openings allow the bass to enter the cabin, but if I do a false wall won't the wall prevent alot of the bass from getting in? If I was to cut an opening in the wall the spans the width (covered either with speaker grill cloth or a something like gutter guard), would that be ok?