FYI you might be able to accomplish this already, without using REDCap. I did very similar to show and dynamically update submissions in Google Earth; by publishing submissions from Aggregate to another server, converting them to KML and appending to a file, and finally pointing Google Earth to fetch from a corresponding URL and specifying a refresh interval. And it looks like you can do similar - ie load placemarks from a URL and refresh - using Google Maps [I've not done it with Google Maps myself, but according to https://productforums.google.com/forum/#!topic/maps/_FeDteewt2I it appears possible].