How can I increase my Samsung Galaxy Tablet 10.1 battery life? How can I increase my Samsung Galaxy Tablet 10.1 (Android) battery life?

I am going to use my Samsung Galaxy Tablet 10.1 (with WIFI and/or 3G) for marketing purposes:
It's going to play a movie non stop (without sound) and there are no other applications running except for the movie. I would like to use WIFI and/or 3G to update the movies that are going to run. But the tablet is going to be mobile and onroute where it's not possible to charge the Tablet.  Meaning I have around 6 and half hours of battery life before I get the first message that my tablet is running out of juice (we've tested that already, but only at one fixed location not in travelling mode (e.g. constantly looking for WIFI connections)). I would like to increase my battery life somehow... I have read some of the other posts here already. So I know that turning of WIFI or 3g would definitely help. But I need WIFI on to update those movies when we come near one of our Hotspots. I know brightness is another thing and that is automatically already set to half brightness. 

Is there a way to create a Samsung Galaxy Tablet 10.1 and Android back-up which has the perfect set-up and configuration for only running a movie (without sounds) and with WIFI on? Looking at a better CPU config and some sort of bare necessities configuration to be operational and saving the most of battery.
According to your usage scenario your best bet would maybe be to get one or more of those external Li-Ion battery packs:

The higher their mAh value, the longer it will last. Currently there are offerings for 12.000 mAh packs, that's about double the size of your current internal battery size. Maybe buy one smaller unit first and see how it performs.

Here's a search link for amazon:
http://www.amazon.com/s/field-keywords=usb%20battery%20pack