Just wondering if anyone knows how much space there is where the radio goes. Specifically I'm looking at replacing it with something that is about 10 inches deep. How deep can the radio be?

 

you MIGHT get 10" if you're lucky, but it'll require moving a bunch of wires behind it and possibly removing some of the support material behind the head unit.
the radio itself is probably 7" deep or so. (it's just as deep as it is wide). I know there's enough room to cram a huge pile of wires in there with it, so you ought to be able to get 10" in there IF you don't have to worry about the wires.