So...after hours of struggling with the GSM unit our grad. student our illustrious IT support guy have gotten it to text us GPS data continuously as long as it was plugged into the computer via USB cable. Unfortunately, no amount of re-wiring has gotten it to function on battery alone. We have therefore thrown in the towel on cellular text message transmission, and are starting completely from scratch with RF transmission via an XBee. Luckily this is something that has been done widely in the past, is well documented on the internet, and we can hopefully get working for proof of concept in a single day. We've even found on Sparkfun's website XBee which has a 28 mile range!

Here is what we are using for proof of concept:

Two XBee PRO series 2 units (one to send and one to receive data):

Two XBee shields to connect them to our Arduinos:

Two Arduino Unos (one in the rocket for data transmission and one on the ground attached to a laptop for data reception):

We will still be using the same GPS unit:

We are currently programming the XBees to communicate specifically with one another. There is a great tutorial on how to do this here:
http://tutorial.cytron.com.my/2012/03/08/xbee-series-2-point-to-point-communication/

Hopefully we can have this working today or early tomorrow and will be able to test it in our rocket.