Self awnser:
Finally, we maked it with an, I dont want to say "ugly" but "not pretty" workaround.
Set the map's operation mode as "just the map", and create markers in JS:
code
var marker = new google.maps.Marker({
position: new google.maps.LatLng(latitude,longitude),
map: CDEmap,
title: "Marker title"
});
marker.addListener('click', CDE_markerClickFunction);
latitude, longitude, CDEmap and CDE_markerClickFuncion are custom JS variables that have to be initialized.