I certainly agree that much more data is necessary in order to actually benefit from it. There really should be a more scientifically designed experiment with a baseline control established... not just a 'quick and dirty' like Rob and I did. I truly expected to see the recorded temperatures from the outside of the box
much lower.
What might make more sense at first would be to use a electronic temperature probe to measure sealed box interior temperatures using 1, 2, and even 3 heat packs over a period of time. Ideally, it would be in a geographical area that has overnight external temperatures into the teens. This could be done by putting heat packs inside the box, sealing it up, making a small hole in the box to insert the probe into the interior, and letting the box sit outside in the cold for about 24 - 36 hours.
The closest information I have seen published on this is from Superior Enterprises for determining what heat-pack to use for shipments:
http://www.superiorenterprise.com/tips.htm