You could add a antihistamine to that list. My big four: Ibuprofen, Antihistamine, Imodium and.. Senokot. Covers pain, swelling and fever; allergies; diarrhea; constipation.
How about a small duffel bag for storage? I'm sure you can get some bright coloured ones that have pretty tough material and waterproof bases so they can be chucked anywhere. That or I would say just a bright coloured dry bag.