Is there someway to make "My maps" in google maps available offline with location markers? I see how to save a map area offline, but how can I make sure the markers layer on"my maps" is saved for offline use? I see how to view it as a layer, but are all the layers saved for offline use?  (Seems unlikely and a waste of resources.)  How do you save a select few for offline map use?
It seems to me that you are talking about your "Starred locations" when you're talking about the markers layer on "My Maps", eih? These are stored in Google Bookmarks and can be exported -- including the locations.

As a general note: The way Googe has setup its Maps/Geo operations leads to a likely reality that Google will "never" provide good offline capabilities. Your proper solution comes from something that does. And that something is increasingly likely using OpenStreetMap. My personal recommendations for apps that can also (easily enough) handle your exported starred Google Maps locations are OsmAnd and Maverick. See OSM wiki for details and more options.