I have a question... or comment. Where did you keep the cooler while traveling?
I ask, because I was going to buy some Dry Ice last year , for a trip I was taking, I started researching it, and it seemed like having dry ice inside a enclosed vehicle wasn't really a very good idea. The idea being that as the dry ice melts, a significant amount of CO2 gets released and could potentially make a CO2 rich environment in your vehicle.
Was this a concern and/or did you not keep yours inside the main vehicle you were driving?