Strikes me this is more a design exercise than recording routes. You already have a record of your routes, individually, if you are trying to get a graphic representation of ground covered, perhaps a graphics program such as the free software GIMP might work.
Make a base map of your area as a .jpeg or .tif. then save individual .png files of the routes. These have a transparent background, so can be used as layers in GIMP.
They can be easily created from my mapping software MM, not sure about others. The route format is not as versatile graphically as the track format. If the saved as a jpg from the map software and opened in gimp the track can be selected quickly and easily and the map erased. All your routes can be saved in a folder as .png files and all these files can be opened as a stack of layers over your base map in gimp. You will have as many colours as you need to individualize each route also additional graphics to add direction and other helpful annotations.