another thought… generate>Vegas… add to png change to image contour and use alpha. Fiddle with settings to get it to be one line and then you can use length as a trim. The only issue I see is that it creates the ‘stroke’ on the inside of the alpha but maybe that’s not an issue! hope this helps
maybe… use auto-trace, then use that mask to create a stroke (generate>stroke) use that to trim stroke, apply the layer style to the new stroke and it’ll draw on and off
*Correction… I forgot about the division on the face, you will need to do that process on each 5 sided shape, and have preserve groups on within the inset tool. and use the collapse command to merge the new points together.
maybe, make editable, select all polys then run inset/ inner extrude command, then pull the new points toward centre of each poly and then merge the new points into one?