On that link, however you need to scroll down to the "RV Rentals" item and click the "More" link.
Tonya, I will also add that while the list/link that Denise provided is the Official List of endorsed Rental companies, they are by no means the only rental companies. Disney may, however, make it more difficult for the "Other" rental companies going forward, so keep that in mind. I am sure others will come by and give you other options. We have our our Travel Trailer, so we don't need a rental.
Keep in mind that the "Sleeping" capacity of most RVs (TT/5ers/Class A, b, c,/Pop-ups/etc...) are a bit skewed (to say the least). They typically will allow for 2 people to sleep on the fold down couch. If it's a "Pull out" into a full bed, maybe, but must are just like a Futon style (Back lays flat) and are hard pressed to get 2 small children on them, not to mention a full sized adult.
Same holds true for the "Collapsible" dinette. They also claim it can sleep 2, but like the couch, you MIGHT get 1 adult on it (if they aren't too tall).
We look at actual BEDS. Some of the bunkhouse models do a nice job accommodating space to sleep. We just don't like to convert our sofa or dinette to a bed in case we want to use it while others are sleeping.
It's good that you are planning NOW for December 2017, but depending on your actual dates (like Christmas or New Year), if you don't already have reservations, you may want to lock that down NOW.
And Finally......
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