If you would like to fly one of the early US Air Mail routes using only concrete arrows and beacon lights as your guide, we have created an MSFS scenery available here https://flightsim.to/file/32132/1926-airway-route-cam5
Each of over fifty arrow and beacon sites has been built for the sim and located using original maps and research by aviation historians.
For an authentic experience fly the route at between 50' and 300' AGL, in marginal weather or at night, with no navaids, GPS or autopilot.