This bit of wisdom came from a site called No Tech Magazine.

Keeping vegetables in slightly damp sand has been a storage method for many centuries. While low temperatures are favourable for vegetables like carrots, high humidity is equally important. Keeping them in wet sand can be a good compromise. In the design above, this concept is improved by burying the vegetables upright, mimicking their growth conditions – and making them last longer, says Jihyun Ryou. Just don’t forget to water them from time to time.

Well, well, well. This could be done with plastic bottles with the tops cut off, sand and water. Much better than water sloshing.
The author goes on to talk about other fruits and vegetables, and their need for humidity or not. And how to coddle all things out of the fridge.

As always, the ugly storage question raises its head. Getting a supply of fresh veggies, with no refrigeration,  in the back of the truck presents interesting logistical problems.