It just occured to me, a couple of small drill bits would work as good as the jewlers screwdrivers.
By your key description, and Sturgis, I assume (I often regret that) that you have a 1991 FXDB. The hiding place is under the seat, where there are 2 open ended tubes. I looped the key to a piece of insulated wire and dropped it down the tube. There's a small hole near the top for the wire to come out of. Then the key wire is just tucked in among all the rest of the wires to be unnoticeable. Yea, you might need a screwdriver to remove the seat (mine has a pin), but thats easier to get than a ride home for the spare key. :34:
I also kept a decent tool kit in the area behind the frame backbone and rear fender.