hmm option 2 is to do all of this in blender-GIS I suppose, that way you get openstreetmap for both the terrain AND the road.
(if you haven’t used blender-GIS yet… there’s some cool youtube videos/tutorials for it, and once you get the design in blender that you want, export to an STL + stl2nc to get gcode and it cuts at high def… some pictures in MDF at Cityscape of Portland OR)