I have a small cooler in my cargo box. The bad thing about a cooler in the box is the cooler is introduced to massive amounts of heat in the box and consequently the ice melts very fast. The exhaust has actually burned through one of my friends boxes, for that reason I put a 3/8 inch piece of heavy duty mud flap under my cargo box to try to isolate the heat somewhat. The ice still melts but seems to last a bit longer than before, and haven't had any burn through as my buddy did