@wolfofpavlov, having more solutions, like the html bridge for google maps, or tuaruas ANEs, is super cool as well, you should share ur experience with it!
Btw, clustering should not be too complicated to implement.
the data has to be processed before rendering, store it in an list, to show the markers at different zoom levels.
If u have thousands of markers, linked lists could be used for fast iterations and RenderTexture for the drawing...
But I definitly understand the need for a most rebust solution. Maps rendering can become a really complex beast to deal with.