Yes, I have done this with ice packs and with other things that have come along somehow for free, but no "Chillows." A small icepack behind my lower back in the seat does nicely for a while. An average person's blood circulates fully once per minute or minute-and-a-half. It's like a human cooling system. Your blood circulates instead of coolant. Instead of a radiator the icepack cools the "fluid" as it passes a cooler surface.
Effect is stronger when you tolerate direct contact with skin!
