I have an 02 tracker 2-door and it is a blast to drive around but it also is very easy for people with sticky fingers to reach into and difficult to secure things in so I did this.
We never have riders in the back and the rear seat bottom has been out for years and with this enclosure I decided it was time to lose the rear seat belt towers to keep it all clean looking.
So I bought a sheet of 3/4" plywood and carefully cut and trimmed it to fit very tight at the upper rear plastic trim.
I used the seat belt tower upper mounting holes to attach a piece of 2"x 7-1/2" angle iron that supports the plywood.
The vinyl covering is a close enough match for me.
The front vertical piece is attached with several angle brackets and I left a small semi-circle to allow me to still use the side cubby holes if I want.
There is enough room to still recline the seats a bit and the space I left behind the front seats has been more usable than I thought it would be.
I carry my laptop with me a lot and thats the main reason I wanted a more secure storage space.
The four bolts holding the top deck on have nylok lock nuts so they cant just be unbolted easily.
I know its not totally secure (what is) but its still a far cry more secure than even a glass window.
I do kind of wonder what might happen in an accident and also what it would sound like with some big woofers on the yellow vertical piece