Might look at DJI Ground Station Pro, Litchi, FlightPlan or Dronelink. The GSP allows a fly over and using images as your route map for waypoints. The feature to use images as map is a 1 time optional cost add-in.
Both Litchi & Flight plan are quick to set up... Dronelink a bit to adjust to their procedures.
All the above allow pre-routing or fly and mark points.
Mappilot is great for a grid too... but no way points.