How can I hide a subwoofer in my 99 jeep cherokee?

I already have a 600 watt Bazooka amp. My car gets broken into a lot and I would like to hide a sub under the rear seat. My amp is already hidden under left side of the rear seat. Can I just put one sub under the left side? What is the biggest size I can use with my amp, and how big of a sub will fit under the seat?