There may be a simpler way than terraforming, download ASTER DEM for your airport, then draw your polygons, they'll be saved as SHP files (I'm assuming, I haven't messed with runways yet), go into QGIS, ArcGIS or GlobalMapper, load both your shp and dem data, highlight the vector points and tell it to assign elevation to the data. You may need to check the values for the DBF file but that should save you a lot of time and effort. You may need to do it on the terraforming SHP file, not sure about runways. Sorry I don't have any time to look into it at the moment drone modeling the house
I'm glad to see that you are exploring adding 3D photogrammetric content to MSFS, and I am looking forward to seeing some screenshots of your future progress with this type of work-flow.