Unless you have refrigeration, bring only whole, unpeeled, washed fruits. Room temperature and cut fruit equals VERY happy bacteria!
If this is just one breakfast, not in the dead of winter, you should consider a not-cooked breakfast; it will be tough enough just getting the coffee water hot. Muffins, fruit, string cheese and previously cooked hard-boiled eggs; maybe granola?
If you want something hot, take a look at the hay box or fireless cook stove. It is the original "slow cooker". You would put the stuff in the night before.
Here are some sites:
practicalaction.org/fireless-cooker- also offers some thought provoking information for a church group.