The path to Jawbone Flats is actually pretty flat and nearly a gravel road. I don't think an appropriate scooter would have much trouble with the path. I would go in the summer when the trail isn't wet. He won't be able to go to Opal Creek and might not be able to go on a couple side trails, but the main trail is something a truck could drive down.
If you stay the night there, you can drive in if you have a handicap.
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