2 lb assorted deli meats
2 lb various cheeses
1 loaf bread
1 case of individual bottled water
1 12-pack of sugary carbonated beverages (If you're a purist, this will be "Mr. Pibb" brand. This can be hard to track down since they've long been out of business, but leading experts still maintain that using other beverages will "curse the donkey crap out of your roadtrip.")
Approximately 173 ziplock bags
Ice. All of the ice.
When constructing a roadtrip cooler, it's important to plan ahead. Some historians say that if Gandhi had planned out his cooler ahead of time, he wouldn't have had to starve himself later on in his travels. Because at some point your ice is gonna melt, and you'll need to spend the traditional 8 hours draining the excess water out of it into a motel sink before refilling it (The cooler) with even more ice. By this point you want your more replaceable items like yogurt and bread to be used up. You can restock those pretty much anywhere. But if you're stuck in some small town in Texas (The "Vast Expanse of Nothingness" State) where there are 4 buildings, and 2 of them are churches, it might be hard to come by some good meats or cheeses.
So the bottom layer is gonna be said meat and cheese, encrusted in ziplock bags. Then cover them entirely in ice. If you're still 100% sure you ever had meat and cheese to begin with, you need more ice. Next you're gonna cram as many assorted beverages in there as possible (Protip: if you've elected to cool down your beer, don't get pulled over. It doesn't matter how closed and sealed your beer is, the police will not be happy. This is also likely true without the beer, but don't rub it in. Don't be that guy.). Again, cover with an avalanche of ice. Now add in your bread and yogurt and miscellaneous sundry items. Sprinkle the top with some more ice and you're all set! Now just close the cooler! Or try to. Because it never closes on the first try, and now you have to play "Sophie's Choice" and decide what you're taking out, and how deep you're willing to shove your hand into the icy depths to get at it. Good luck! Maybe you'll drive past a hospital to get that frostbite looked at. As for me, I'm off. I might say hi again from the road along my way! I might not! It kind of depends on whether I can get an HD picture going on these cactus fields.