Initialize MapFragment programmatically with Maps API v2

I'm trying to add a MapFragment to my current Fragment. The use of nested fragments is restricted to FragmentTransactions, you can't use the xml tag in your layout. Also, I want it to be added to the main Fragment when the user presses a button. So, I'm creating the MapFragment programmatically with getInstance() when the user presses that button and adding it to the proper place. It is shown correctly, so far so good.

The problem is that after attaching the MapFragment I need to get a reference to GoogleMap to place a Marker, but the getMap() method returns null (as the fragment's onCreateView() hasn't been called yet).

I looked at the demo example code and I found the solution they use is initializing the MapFragment in onCreate() and getting the reference to GoogleMap in onResume(), after onCreateView() has been called.

I need to get the reference to GoogleMap right after the MapFragment initialization, because I want the users to be able to show or hide the map with a button. I know a possible solution would be to create the Map at the start as said above and just set it's visibility gone, but I want the map to be off by default so it doesn't take the user's bandwidth if they don't explicitly asked for it.

I tried with the MapsInitializer, but doesn't work either. I'm kind of stuck. Any ideas? Here is my testing code so far:

public class ParadaInfoFragment extends BaseDBFragment {
// BaseDBFragment is just a SherlockFragment with custom utility methods.

private static final String MAP_FRAGMENT_TAG = "map";
private GoogleMap mMap;
private SupportMapFragment mMapFragment;
private TextView mToggleMapa;
private boolean isMapVisible = false;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment