Just wanted to update everyone.
Everything went well. I did a layer of about 24 frozen water bottles, stacked all the meat in, then topped it off with about 30 ice water bottles. 4 days later (or roughly 3 days and 15 hours) everything was ice cold minus one package of hamburger that was getting a bit soft, and a package of steaks that were getting a bit soft as well. Not sure if I didn't pack the bottles as tight on that side or what, as they both were on the same side, but nothing else around them had that issue. Regardless they were still cold and nothing to worry about, but was interesting.
Thanks again to everyone who replied and gave me advice. Obviously if not inside a car dry ice is the way to go, but the frozen water bottles indeed do the trick if you have the space for them in a cooler and are limited to interior storage in your vehicle.