A vital key to success with the GFCF diet is to always be prepared. That means having appropriate food, snacks and beverages easily accessible when needed. I always carry a snack for the kids in my purse in case hunger strikes while we are out and about. I also keep a supply of snacks for them at school and daycare.
Now, we are in the midst of a busy tropical season. Since we live on the coast of North Carolina, we know that we must be prepared for hurricanes and the resulting power outages, flooding, and lack of fresh water. Click this link to see FEMA's recommendations for an emergency supply kit: http://www.fema.gov/plan/prepare/basickit.shtm
Tropical weather is not the only potential disaster or emergency that could happen, so it's a good idea to be prepared year round. Our emergency kit includes all the usual items such as flashlights, batteries, canned foods, water and first aid supplies. In addition, I keep it stocked with shelf stable GFCF foods. You'll want to pay attention to the expiration dates on these items and rotate your supplies accordingly. It's also a good idea to have a small supply of toys and diversions for the kids as part of your emergency kit.
GFCF Mommy had a great post on preparing for a hurricane: http://gfcfmommy.blogspot.com/2008/08/we-interrupt-this-blog-for-message-from.html
Many people recommend keeping a second supply of medications for your emergency kit. This practice is not always affordable, so I keep a list of our medications and supplements. That way, I can just grab and go if necessary.
Hope this information helps. Being caught unprepared could easily sabotage your child's diet (and progress), so why risk it?