Just so you know, driving from Fort Wilderness to the MK might be counter productive.
Internal buses run every 10 minutes to take you to the Settlement Depot, which is where you can catch the boat to the MK. The bus ride is less than 5 minutes, and the Boat ride isn't too long either.
Another option, at the Settlement, there's a short bus ride to the TTC, which is where you'd be parking anyways. The TTC bus cuts through a little shortcut that only the buses can use. From the TTC, you can take the Monorail or Ferry.
If you drive, you have to take the LONG way... going around by Port Orleans, OKW, Epcot, and then around that way. From FW, it's at least 20 minutes to the MK Parking lot.
Parking is free, however, just as a caution, the AAA lot is not serviced by the trams, and is a small walk to the actual TTC. (5-10 mins)