Hi
This is going to be a little vague, sorry.
You could use widgets to display the town names. When placing the signpost blue print, you might be able to get it to search for the closest town, get the town name maybe from a data point in that town and auto fill in the widget.
Would be a little work to start with, but then you just to put them in the map and done.
Other way, make Structure / array of all town names, make it editable, then when you place it, use the drop down in editor to choose town.