I've left cars in Maybell a couple of times, most recently in 2012. I think it was with the folks at the Maybell Store but I can't remember. IIRC it was about $5 per night. Cheaper than just the gas up to the put-in and back to Maybell, much less the shuttle.
Have a good trip,
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse