1You need to determine the temperature range in which the fruit loaf tastes better.2 What is the likely range of outdoor temperatures in your own area of operation, and what is the time that a normal insulated box can support, and what is the size of the time difference in sales you may need to make.3Perhaps you can extend the holding time by adding ice packs to the insulated box, etc.

I'm afraid you need to experiment with this problem on your own.