You didn't mention whether you were bringing a cooler. I will assume not, since you are bringing your food in a duffle bag.
Peanut butter and jelly sandwiches (or at least the stuff to make them)
juice boxes (yes, even for adults!)
Jerky (I hate it, but I know people that really like it, any time of day)
home-made trail mix (that way you can control the amount of sugar in it)
Shelf-stable pudding packs (again, not something I would care for, but in a pinch it would be a reasonable breakfast food!)
apples, bananas both do well without refrigeration
dried fruit such as apricots, bananas, etc. Very high in sugar, but at least there is some nutritional value!
prepackaged peanut butter crackers or cheese and crackers.
THat is all I can think of for now.............P
BTW, have you considered either mailing a box to the resort ahead of time with this stuff, or using a shopping service? Look around here... there are lots of threads on both topics...........P