I like this one.
Let's leave aside the fact that there is a crane / barge available and look at this problem as if there isn't.
If ringle's mate simply doesn't have $600 at hand, the barge is not an option.
A deck stepped mast can be reasonably safely lowered with a gin pole rig.
A keel step mast is a completely different story. It will have to be raised straight up until it is clear.
Southace's suggestion of rafting a boat either side solves this problem really neatly.
But, what happens if you can't round up two boats to help out.
A lot of thought and preparation would seem to be the key to success on this one.
There is a very good video of a keel stepped mast being removed from a catalina 27
The guys on SV Pestilence borrowed a davit from a cruiser.
Gary