I heard of a community who tried to shared bike thing, borrow one when you need it and leave it parked at a visible spot when you're done. As I recall it didn't work out too well because they started on a huge scale and kept misplacing the bikes.

I do remember that they painted them bright gold and posted up community notices, maybe you could do something like that...make it visible and available with an attached note or plate saying where it's home is?