Hum. You have on prominent display there the very thing that prevents me from doing more bike shopping: milk. And lots of it. Being from Maine I have to assume that the grocery store is farther away than mine and that the milk is stupid expensive, yet you have no issues with just tossing it in the trailer by the gallon like that. How long do you find it to be OK to leave milk, and other perishable or frozen items, out like that before things start to go, well, bad?