Without having been back there myself, I can tell you there's enough room for an alarm system control unit, but not enough room for an aftermarket DVD player, which is a little smaller than a single DIN head unit
Thats how come mine ended up under the glove box, near the passenger's knee. Not ideal, but I didn't like how much abuse it would get under a seat, and I was running out of ideas. What kind of system are you trying to set up? Just rear seat DVD?
I put the aftermarket Clarion Pro Audio head unit in my dash, which has a 7" screen and DVD player built in. I then put in a second, Audiovox DVD deck (the one under the glove box), which adds capability for a separate DVD to run to the rear dop down screen, and also has the inputs for auxiliary (playstation, etc.)
Well I have all Kenwood-LZ-800w screen, Z910DVD, 650d amp, door speakers, and a 12" sub. My X already has the stock rear dvd but I am planning on just havnt got the Kenwood NAV system. The reason I got this x was that a buddy is a sales manager and he drove it for 4500 miles and I got a really good deal on it. But I have all this stuff sitting in the corner waiting to be used
I'll tell you what. Your idea sounds like a great install, especially with navigation capability. I honestly don't know how much effort my shop went to when they told me it wouldn't work. You might want to look in to it a little more before you give up. I have not personally seen how much space is back there, and I'd have trouble sleeping at night if I found out you trashed your plan, and I was wrong.