Hi there!
Awesome project!!!
I know you said earlier, you might incorporate a TV, well I had an idea for you, that I used in my camper.
There are no free TV signals any more, unless you're right next to a city and get HDTV.
Could go with satellite, but then you need the reciever and card and subscription.
What I did, and what I propose you could do, is order one of these :
http://dx.com/c/consumer-electronics-199/hd-media-players-103/android-hd-players-191
They are little android boxes, that hook up to a TV.
Just plug in a wireless keyboard and mouse, and plug in a USB stick or USB hard drive,
and you can play movies or music through the android box!
Could also plug a surround speaker system in I imagine!
Those android players are as cheap as 50$ shipped, we have them all over our house now haha.
I have one in my camper, and we have a 2 TB usb drive, it's got about 900 movies, several tv shows, and 15,000 songs on it!