In order to fix the compilation error above, I think that you have to overload the constructor of each of your custom renderers.

Here is an example using a ButtonRenderer. Hope this helps (I'm just discovering Xamarin.Forms)

[assembly: ExportRenderer(typeof(CustomButton), typeof(CustomButtonRenderer))]
namespace MyApp.Droid
{
public class CustomButtonRenderer : ButtonRenderer
{
public CustomButtonRenderer(Context context) : base(context)
{

    }

    protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        base.OnElementPropertyChanged(sender, e);
        //ToDo: Customize Button
    }
}

}

Is there a way to create this without have a dependency on Xamarin.Forms.Maps ?

I've been trying to do something like:

public class MapControlRenderer : ViewRenderer<MapControl, global::Android.Gms.Maps.MapView>, IOnMapReadyCallback
{}

But so far no luck. It would be good to have something we have complete control of and knowledge of how it works. I've done this for IOS - it worked well.