Hi, Jamie! There are areas at Fort Wilderness campgrounds that are pet friendly, so when you make your reservation, just let them know that you will have your service dog with you.
Service dogs are welcome throughout the Walt Disney World resort and theme parks. There are some restrictions, however. Pets are not permitted on some attractions, and there are restrictions with regard to accessibility for service animals at other locations. You can find more information about where your service animal might be permitted by clicking
Service Animals at Walt Disney World.
Whatever documentation you have to indicate your dog is a service animal is going to be good to bring. Cast members are generally familiar with the traditional service animal, but as emotional support animals are still a fairly uncommon type of service animal, documentation from your physician or from whatever training your dog has had might be handy.
Have an absolutely wonderful vacation!