rei.com/platypus . There is a pic of mine posted above. There are many companies now that make soft water bottles, and I found some at Dollar Tree dollartree.com. They are thinner, but do the job as well! And if you go to their website, you can order them by bulk (48 of them at a time). They come with a clip so you can hang it off the side of your tote bag. Just search under "waterbottles" and they will come up...or just check out your local Dollar Tree store. I found mine by the soda section. They come in many colors and make great gifts. If you find them in your store, buy alot of them ( I bought 10!). There is a pic of one posted below.
Now for you're food. How do you keep it cold. A refillable ice pack..like the ones we used as a kid. Fill it with ice before you leave the house to keep your meal cool..then dump the ice before you go into the airport..your food will stay cool. Then once you get through security, go to the nearest concession stand and buy a cup of ice. Once you get onboard, we dont mind giving you ice. Some people use baggies to store their ice. If you double them up, they work just as well. Also put your refillable ice pack in a baggie because it will "sweat" and you'll have a little "puddle" in your cooler.
How do I keep salad dressing? I found the cutest salad dressing holder at Bed Bath and Beyond by Everiholder everiholder.com. It's 3oz and it can hold your favorite salad dressing ( enough for one large salad). There is a pic of it below. $3.99. Also, I have learned to hoard package salad dressing whenever I can find them. They will slip right into your 1quart baggie . And most dont have to be refrigerated. When you see them, grab a few and keep them. Au Bon Pain also sells their salad dressing for 50cent a package.
These are just a few of my tricks. Eating well and staying fit while traveling takes a bit a planning , but the results are well worth it!