There's only one problem...what if you get a flat!
JL makes a Stealthbox for your car. It slot loads one 10" (I think) in the passenger rear corner of your trunk. It's a very stealth look and will take maximum advantage of your available trunk space.
If you don't like JL, or the price is a bit much (they are not cheap) you should look at a 10" or 12" that will work well sealed. This will give you the best compromise between SPL and trunk space. It's also very easy to pull off. I run a single IDQ12, and it's enough to keep me happy and make the hair on your neck stand up!!
There are plenty of options out there for sub choices.