You are correct, there is no car parking at Trail's End or Pioneer Hall. That area is called "The Settlement". In theory, your wait for a bus could be up to 20 minutes, usually a lot shorter. A lot of people rent golf carts or bring bicycles, there is plenty of golf cart/bicycle parking up there. If you're in good shape, depending upon which loop you're in, you can also easily walk because there are lots of trails. I think the cabins are anywhere from 1 to 1.5 miles from the restaurants.
We camp at Ft. Wilderness every year and bring our bicycles. We tend to walk or ride every where and just avoid the internal bus system since we're all able bodied.
Which park are you thinking of going to? You can take a boat from "The Settlement" to MK - very quick. We also take the boat to the Contemporary a lot and then hop on the monorail to go to Epcot. It's just fun, even if it's not super quick.
You don't really need to drive your own car anywhere. You can catch a bus from "The Outpost" (which is very close to the cabin area) to Disney Springs, the water parks, AK or HS. (And buses to Epcot and MK too).