Those should work fine.
I once got a moose in northern British Columbia, a 2-day drive from my home in southwestern Montana. In addition to a 120-quarter Igloo, I still had some waxed boxes with Styrofoam panels that a fishing lodge in Alaska had used to pack my frozen fish for the flight home. I took those too, and was able to fit the moose meat in the cooler and boxes.
It was mid-September, and plenty warm for most of the drive. I just made sure there always plenty of ice on the meat, and it made it home in fine shape.
