Fruit is all carbs…
The other things you mentioned can be done as snacks throughout the day even without access to a kitchen.
Pre-cook a sweet potato and eat it during the day - they are a great snack (I eat them room temp all the time)
Make yourself some overnight oats and eat in the middle of the afternoon
Get some veggies (cooked or raw) and snack on them throughout the day
Plenty of filling slow carb options you can have without a kitchen handy - you just have to do a little prep over the weekend