Hi Edward!
Fort Wilderness Resort is my home away from home when we head to Walt Disney World. We will actually spend 2 1/2 months there this fall and I can't wait!
Many guests love the idea of camping or as I put it "glamping" at Disney but they don't have the vehicle to make this possible. There are indeed some reputable companies who rent all types and sizes of RV's and will come and deliver them to a site and hook it up for you. They give you the simple instructions and you are ready to enjoy your stay.
Your best bet is to google "Walt Disney World Camper Rental" which will take you to several sites. Look through each to see which fits your needs best and then call to ask the important questions. You will want a unit that is fairly new, will it include all cooking utensils and appliances, does it include linens and towels, you will expect a clean camper, will they hook it up for you and pick it up on check out day, is there a number that you can have that will reach someone 24 hours a day in case of issues or emergencies. This last one is very important as if the AC goes off or the plumbing stops you will want to be confident you can get help immediately.
Disney allows camper rentals in the resort but they are not responsible for them once they are delivered and set up. It is a fun way to experience a Disney vacation and I have had many friends rent and enjoy their new homes for a few days.