I don't have room under my seats since I have them dropped all the way down for driving anyway, but if you use the right form factor, you can put it under the dash. I was going to mount mine above the glove box with access from inside the box top.
The 7" tablet just fits perfect. I just haven't settled on one yet. The Kindle Fire is a strong contender, but a quad core is in the works. Whatever it is, it will be rooted and wiped clean first.
