Greetings, Kate!
It sounds like your family is planning an incredible Walt Disney World Resort vacation! It is certain to be a celebration your parents will cherish.
The Campsites at Disney's Fort Wilderness Resort are beautiful and we love visiting my parents each time they bring their motorhome down for a stay. While there are a few sites with pine trees, most of them have more low bush-type surroundings, so the chances of you getting a site with trees and properly spaced where this type of tent would work is very limited. In case the odds were in your favor, I called the resort to ask and unfortunately, the official word I received was no, they do not allow items, including tents, to be tied or hung from trees. Perhaps you can find a small, traditional tent to bring with you or tents are available to rent from Disney for your stay.
Thank you for visiting the Disney Parks Moms Panel with your great question, Kate, and let us know if there is anything else we are able to assist you with. Have a wonderful vacation and please wish your parents congratulations from all of us here at the Disney Parks Moms Panel.
Pixie Dust,
Lauren