OK, I'm slightly confused. Do you want to go to Wilderness Lodge (a Disney Deluxe resort hotel) or do you want Fort Wilderness (campground and cabins)?
I will assume that you are looking for Fort Wilderness, so I'll work with that.
Cruise America is the largest RV rental company. They have a location in the Orlando area:
Cruise America
2915 N. Orange Blossom Tr.
Kissimmee, FL 34744
(407) 931-1409
Now, I admit I have never rented one, but from what I have been told the largest cost is in the per mile fee. As I understand it you pay a per day fee which includes a set number of miles (i.e. 250). Anything over that you pay extra for.
Renting in the Orlando area would save you the mileage fees, but then you have to pay airfare, pick it up, return it and so on. Additionally, you have gas for your car and/or airfare.
Renting in NJ you now have mileage fees and gas for the RV.
A third option is the cabins at Fort Wilderness. They allow you to stay at the Fort but don't need an RV.
I would price it all theree ways and see which works out best.
Just for the heck of it I used their quick quote function for a week and this is what I got:
Pick Up Location Kissimmee, FL
Drop Off Location Kissimmee, FL
Pick Up Date Tuesday, August 10, 2004
Drop Off Date Tuesday, August 17, 2004
Number of Nights 7
Compact RV $882
Standard RV $882
Intermediate RV $980
Large RV $1,036
Miles Included 700
(Unused miles are refunded at the rate of 29¢ per mile. Excess miles are 29¢ per mile. )
You can probably figure you will take about $150 (500 miles X $0.29) off their prices as picking up in the Orlando area you probably won't drive more than a couple hundered mles. It's nice they refund unused miles.
Good luck.