Look into Jeep products... I use a "Dirty Dog" rear cargo net above my back seat area for this exact purpose. The "cargo net" is more of a netting for use when the Jeep top is all off - but for me, I leave the hard top on all the time and the net works as an "attic stuff space". Of course, you'll need to do some measuring to see if it fits!
The netting doesn't stretch so therefore sits as tight as you make it, and also it won't wear out and over stretch like those cheap elastic nets you can get. The "holes" also are large enough to stuff winter gear such as sweaters, light jackets, hats, mits, etc.
Sorry for bad photo, I'm sure I have something better somewhere. Clicking through to hi-res photo will also give you a link to the product I use to check for sizes if you want.

Attic "Stuff Space" in the Jeep - dirtydog passenger netting by
e j, on Flickr