Panel audio idea.
 

I have an 07 Panel I hope to have running soon. I want to know if anyone has put speakers in the rear side window pockets?

Not sure exactly where you're talking about. Pics.

https://cimg2.ibsrv.net/gimg/www.che...b31309d21.jpeg
The panels don’t seem deep enough to install speakers, and attaching a box would take up cargo space

Rear side Window pockets ?

The recesses in the cargo area of a panel HHR, where wagons would have had windows.

Where the window would would draw down to, if there were windows, behind the door card.

https://cimg9.ibsrv.net/gimg/www.che...91d5db026.jpeg
In the red outline

This is a door card. My guess is the mounting is in the door , just cut a hole and put a grille on it.

https://cimg8.ibsrv.net/gimg/www.che...a392d9b17f.png

But there’s only an inch between the rear 1/4 metal and the panel

There seems to be room. There is a speaker in this one.
https://cimg2.ibsrv.net/gimg/www.che...0ad18523f.jpeg