A shorter way to create the transparent map is to open gpx2img program, upper left drop down menu gives you the option to load gpx tracks. Keep adding all that you need, then save. The data is saved in mapsource as "gpx2img" so open mapsource, select all the maps you want from the drop down menu, including the "gpx2img" map and send to device (sd card or gps internal memory). Once transferred, you can select which map you want displayed on your gps including the gpx2img map (transparent) so you will have selected to 2 maps to be displayed on your gps. Since the gpx2img map is transparent (overlays the other map) you will not have any map conflicts displaying them.
There is a tutorial within the help file in the gpx2img program as well.
Hope this helps, and not hinder the discussion.