[jluv]

Yep, 5x7/6x8. Not hard to get to. You'll need a star bit to get the seat belt anchor off. It really won't take more than 5-10 minutes per side if you hump it. Anything better than stock will be a noticeable improvement. Don't dump too much into the rear speakers, though. Front is much more important.

 

[jluv]

Coaxials will be fine back there, and much easier than messing with separates. I'd still get a decent set that has passive crossovers. And yes, there is probably room for crossovers back there, but you have to make sure it doesn't interfere with the seat belt or clips. I planned on doing mine that way, and ended up scrapping the idea and mounted the crossovers under the rear seat.