I understand, some months ago I had no idea of these tools. Globally you could look at tween curve discussions.
There is a slight problem with Proximity has it searches for 2 points, it is OK if points are inside the curve but if they are ends it generate some problems. Topologizer from Daniel Piker could help.
And also your problem is more a Medial Axis problem, there was some discussions on it in 3D but I think it is more appropriate for Solids.