Hi ahull,
Correct on temp but the payload will not be at peak altitude long enough to saturate to that temperature level. I have crewed on many of flights that were far less sophisticated than I as far as insulation and heating. Granted, most were using GoPros. I'm the only one I know that is using this model of Canon(SD1400). Knowing that recovery is not a sure thing, I'd rather try to make a $40 Canon work than a $250 GoPro.
The freezer is close enough without spending more time and money on tests than the actual launch. That's what makes it fun is a little of the unknown. Yes, I have even looked at vacuum chambers to test the pressure sensors. But in the end, each launch is it's own test of various subsystems and you get the added bonus of some cool pictures along the way. The launch and recovery are a blast because you get your friends and their kids involved and even with a SPOT tracker, the recovery is like a treasure hunt. Oops, I'm babbling, sorry.
Thanks for the link! I always enjoy checking out the ingenuity of others and their low cost, effective ideas.
RE: "results of my previous flight with the canon." I don't have a good pic of the results of it hitting the ground at ~50mph, but the lens was still extended and was bent about 30degrees down

. My homemade PCB was cracked in half but the SPOT tracker still worked.
At the risk of going of topic, I'll post the last two pics from my latest flight that I am referring to. I recovered the payload with everything intact this time. I apologize to the mods in advance.
Update: Couldn't bring myself to cut down the resolution to post here. So here is a google drive link of all the pics from Sunday's flight:
https://drive.google.com/folderview?id=0BxUoz5Ay87KOR2tISkpIODc3T0E&usp=sharing