If it is only about pulling the shapes closer together, rather than specifically creating a curve wrapping around them, a simpler way could be to connect them all with weak Coincident goals like this:
Circle Packing_CoincidentPull.gh (28.2 KB)
Also - I see here you pack circles then fit polygons in these circles, but if it is actually the polygons you want to pack closely, another option would be to use CurveCollide on the polygons directly.