1. I would actually be wary of the cool towels in truth. They often are deceptive in what the offerings actually are and how much they cool you may be not nearly as effective as you are hoping for. The alternative is a very easy one. Bring a wash cloth and get it wet with the coldest water you can get. Reuseable 100% of the time and its a hell of a lot cheaper.
2. Need an ice pack? Bring along a couple ziplock bags. Not only can they be helpful protecting valuables on water rides, they also can be used as a quick ready made ice pack.
3. Ever consider freeze drying yourself? Get drenched and then goto the coldest place you can find. The colder the better. Now your clothes will take a while to cool down but all the coldness will get trapped in your clothes. As soon as you walk back out into the warm air you will notice a remarkable difference as your clothes will feel a lot cooler but still be wearable.
4. Do not buy icecream unless you are drinking water at the same time. Icecream can actually dehydrate you if your body is desperately craving water but all you are giving it is milk and sugar.
5. You don't need a cup of water for washing your head. I call this the instant water ride. Bring along a hat. In the bathroom or a drinking fountain, fill the hat up with water, and then dunk the entire thing right on your head once you are outside. You instantly will soak your head, neck shoulders, upper abdomen, and maybe your feet if you had the wisdom to wear flip flops. Baseball caps are good but don't bother if you are just wearing a visor.
6. Schedule your trips around the weather. Do the high priority attractions first, then as it gets warm you hit the water rides, then have lunch at an air conditioned restaurant, go on some indoor rides, then go on some water rides, and by then the afternoon will begin to cool down as sunset approaches.
7. Mist fans are a vanity item that gives little benefit to cooling your face. Just use the restroom and wash your face in the sink. You will get a lot wetter and it costs you nothing.
8. Free refills are good but be wise about what you drink. Some drinks may taste great but the dehydration isn't gonna be so easily reduced if your drink consists mostly of corn syrup. In the end nothing beats dehydration better than good old fashioned water. You can add a little lemonade for flavor but sticking to the water may be far more effective than guzzling down a soda.
9. Avoid machines that offer to dry you out. They are not nearly as effective as promised and some I have encountered have mold issues. The best alternative is just go on more rides or find a spot with direct sun exposure without wind.
10. Pace yourself. Rushing in the first hour or so when the park opens is not a bad idea but over time you need to reduce your momentum and carefully adjust your decisions based on how you are doing physically. Many people end up at their worst cause there is a completionist desire to do everything but I can tell you from experience that is a bad idea. Take your time and enjoy the park wisely. Don't push yourself too much or you will just end up tapping out early.