How in api map google v3 not to show tiles that fall under mine?

Question

Google

Didn't think of anything better than intercepting getTile completely.
Here is a section of the code of my example converted from code.google.com/intl/ru/apis/maps/documentation/javascript/maptypes.html (section "Base Map Types").

CoordMapType.prototype.getTile = function(coord, zoom, ownerDocument) {
	var div = ownerDocument.createElement('DIV');
	div.style.width = this.tileSize.width + 'px';
	div.style.height = this.tileSize.height + 'px';
	if(*check for my site or not mine*){
		div.innerHTML = "<img src='http://site.ru/"+zoom+"-tile-"+coord.x+"-"+coord.y+".png'>";
	} else {
		div.innerHTML = "<img src='http://mt1.google.com/vt/[email protected]&hl=en&x=" + coord.x + "&y=" + coord.y + "&z=" + zoom + "&s=Gali'>";
	}
	return div;
};

There is a need for this ... when drawing a section of the map, Google tiles come out faster and are visible for some time before my tiles are drawn.

I think that this is not correct, since the addresses of Google tiles may change. My version works, but for how long.