Using geojson in a C# class with in ASP.NET core and MongoDB

I'm trying unsuccessfully to create a MongoDB GeoJsonFeatureCollection from JSON in ASP.NET core.

(environment: MongoDB C# driver v2.10.2, ASP.NET core v3.1)

// a C# class which contains my geoJson features and intend to store in MongoDB
public class Route
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; }

    public GeoJsonFeatureCollection<GeoJson2DCoordinates> Data { get; set; }
}

Then in the ASP.NET core controller, I'd like to have incoming JSON auto-converted to the Route class:

[HttpPost]
public ActionResult<Route> Create(Route route)  // FAILS HERE WITH NO PARAMETERLESS CONSTRUCTOR ERROR!
{
    _routeService.Create(route);  // send it off to MongoDB
    ...
}

I understand that this fails because MongoDB's GeoJsonFeatureCollection doesn't have a parameterless constructor, so the incoming JSON can't be automatically mapped to the C# Route class. But I can't seem to find an obvious workaround to this situation.

Possibilities I've considered:

1. Skip trying to map to a C# class and just work with BsonDocuments for everything. It seems like querying becomes a bit more complex with this option, and I lose the power of C#. Seems to be advocated here.

2. Somehow add a custom serializer for GeoJsonFeatureCollection. I have no idea how to do this, but there is a possibly relevant serializer provided in MongoDB:

   https://github.com/mongodb/mongo-csharp-driver/blob/master/src/MongoDB.Driver/GeoJsonObjectModel/Serializers/GeoJsonFeatureCollectionSerializer.cs

3. Use a string to hold the geoJson Data in my C# class and perform the conversions manually:

   public string Data { get; set; }

   instead of:

   public GeoJsonFeatureCollection<GeoJson2DCoordinates> Data { get; set; }

   and then manually convert the string to a GeoJsonGeometryCollection via:

   var geoCollection = BsonSerializer.Deserialize<GeoJsonGeometryCollection<TCoordinates>>(json);

   but this seems ugly, requiring an extra JSON serialization in my javascript code and manual conversions in every HTTP endpoint.

What to do?