Car & Network - thoughts...

[nickp]

So I'm new to this XBMC/RPI thing, so forgive the not-very-well thought out questions...

So, I'm trying to put a video server into my wife's new car (Honda Odyssey) and trying to figure out the best way to do everything...

I'm trying to do everything low-power, and do not want any 100v devices, desktop routers, or anything else that is large in the car.

I have the RPI (B+) with a small UPS (http://www.piups.net/).
The PI boots up when power is supplied, and shuts down (gracefully) when power is removed.
So far, so good.

However, in order to control the PI, I need keyboard/mouse or a remote control.
I figured the easiest way to do that would be to use the iphone/android app (is there an RF remote control option?)
In order to use the iphone/android, and need to be on the same LAN as the RPI.

So, I need a network in the car.
I was thinking of doing this is two different ways, and wanted input on the best way to approach this.

Firstly, I could use an old MiFi type device in the car.
Pro's:
Very easy to setup.
XBIAN will see it as regular WiFi network, so easy to configure server.
Phones/Tablets will see it as a regular WiFi network, so easy to configure controllers.
Cons:
Don't know if MiFi will work without SIM (ie no service.)
Don't think MiFi can auto power on.
If MiFi is advertising network with no Internet, then all phones that connect to it will lose their internet connection for the entire time in the car (a bad thing - no email, etc.)
I might have to activate service on the MiFi to alleviate some of these issues, but do not know about the power on thing.

Secondly, I could turn the RPI into a router.
(Not sure that I know how to do this, but it's linux, so it shouldn't be too hard...)
Have 2 WiFi cards in the RPI.
The WAN WiFi card would be a "client" and would connect to a 2nd WiFi network in the car what it was available. (ie, from a MiFi or mobile hotspot on mom's phone.)
The LAN WiFi card would be the "router" and would advertise a car-network, that all the kids phones & tablets could connect to.

The advantage of the 2nd approach is that the Car-WiFi would always be on, so the remotes would always work.
Mom could then choose to turn on the MiFi / Mobile Hotspot in order to make the internet work on the car WiFi.

Issues with the 2nd approach.
Not sure that I know how to do this yet, but am fairly sure that I can.
Not sure about the performance hit the RPI would take from being a router.
Not sure how fast the router performance would be (would we get a 1Mbps, 10Mbps, etc.)

I will be using the RPI for watching movies, not for streaming audio.

Does anyone have any thoughts on this?
Sorry if these are dumb-sounding questions.

Thanks.
Nick.