Freeze them overnight prior to your trip starting. Nearly all of the motels we stay at have refrigerators in them, so stuff the burros in the mini-freezer overnight. They stay frozen for me through the day. Plus, if your crew lounge is close by, I keep them in the freezer there when I can, too, just to keep them solid for longer periods of time. I've been doing the burritos for about three months now, and they won't thaw completely on me, even in the heat of the summer. Haven't gotten sick off of them either, so that's a good thing!