I know you said efficient, but let me just give an alternative. If it is a day that the MK is open late, you can just leave your car in the MK parking lot and take the monorail to the MK, and then the boat to Fort Wilderness. (The bus stop is near the boat lanuch.)
I think this is the most pleasant way to go, and the boat lets you off very near Pioneer Hall. I love this, because I just live to avoid buses, and the boat ride is very nice.
Just don't do it if you'll be leaving Fort Wilderness after the MK is closed, because then the boats will have stopped running and you'll have to take a bus back to the TTC and then the MK -- not fun or effecient in the least!!!!