There is a hill that people use.
Once you drive into the Fort and get past the checkin area you will pass the big bus stop (The Outpost Station) and drive by the barn/corral area where they give horse rides (both the corral and bus stop are on the right).
Driving past those and further up on right you will come to a small service road that goes back to the Fort's shed/shop area. Signs are posted for guests not to enter but the Fort lets us use the nearby hill. There is a hill running about 6-8 feet high parallel to the main road that is covered in grass (I think it was built when the Fort was new to block the view back into the shed/shop area). It is on either side of the service road. If you drive up to the road on the left that goes down through the cabin loops, you've gone too far. You only have to drive 10-20 yards on the service road before you get to the hill.
People pull off to the side of the service road and use a portion of the hill in the grass to back their cart off of, say, a pickup truck bed. The slope of it isn't bad and although I've never seen it done, people have posted here in the past about using this hill for that purpose.
Bama ED