Speaker panel?

My duster rear seat folds down forward. It has latches at the top.

There is about a 1 1/2 feet of storage space inbetween that and the fold down that goes into the trunk. When both are upright there is a shelf under the back glass that comes out about 10 inches all the way across and has a factory edge (nobody cut this up). In between THAT and my upright backseat there is a halfmoon shaped gap about 10 inches wide all the way across that something needs to go in.