Type 1 diabetic here (for the past 30 years), and I've found that the big things for me are:
1. Everything seems a little bit magnified: the activity level isn't just higher, it's fairly constant, so your muscles may not stop asking for fuel, which means blood sugar will be lower than normal. Similarly, when you do stop activity, it's usually to sit down and eat, so the carbs will be hitting when your body is not requiring more fuel. So, any adjustments that you make with insulin should be slow and gradual.
2. For equipment, because of the pens, you may want to get (if you don't have one already) one of the little cold packs from Frio or another manufacturer (and I haven't used them, so I cannot make a recommendation) for keeping things cool in the Florida heat. I'm on a pump (OmniPod) and haven't had trouble so far with the heat causing any degradation of insulin efficacy, but having a static store of insulin, like a pen and refills for the pen, would cause some concern if it were not kept cool.
3. Stay hydrated and keep cool. For me, getting too hot and dehydrated can mask hypoglycemia symptoms.
4. Make sure to indulge a bit. Okay, so maybe the chocolate chip cookie ice cream sandwiches that are as big as a 5yo's head are not the best thing for a T1 diabetic, but there are plenty of little indulgences around the parks that have sugar in them, and as long as you're monitoring blood sugar, you can offset those with insulin and exercise. Also, keep in mind that sugar-free offerings often have just as many, or close, carbs as the sugar-ful ones. And they taste worse, invariably. That being said, the restaurants do put out some very good no-sugar-added desserts that may be more healthy in general.
5. Along with that, sugar to treat hypoglycemia is usually pretty handy. If you get caught out without something, a quick trip into any store will let you get your hands on some prepackaged candy.
6. Work with the chefs in the restaurants. Disney (at least at WDW) is great about all dietary concerns, and you can usually talk with a chef at the TS restaurants about the nutritional information for the dishes. Counter service restaurants may be a little tougher, but it never hurts to ask. Low-carb options may require you to venture into the adult side of the menu at times, as a lot of the kids' offerings can run to mac and cheese, pasta, Uncrustables, and the like.
7. Have fun. Your DD is still the same kid, and will enjoy all of the same stuff. Looking at Disney as an enemy (Ack! Carbs in the food! Ack! Lows from walking around all day!) can add stress to your life, and to hers, as well. Just keep up your regular testing, make sure you calibrate her CGM if she has one, and test before giving any insulin, and know that, should anything happen, Disney has first aid stations in every park, and lots of cast members who are there to help you.
Good luck, and enjoy your trip.