Online und als overlay habe ich diverse Möglichkeiten gefunden, aber dass sich der jeweilige Weg/Track wie eine gpx Datei verhält -was das absolute Optimum wäre-, dazu habe ich noch keine Möglichkeit gefunden.
This may not answer your question :
As you know,you can download all routes as a GPX or KML from the site you mentioned.
Unfortunately, the GPX is not a useful format as route segments generally are not plotted systematically, making the gpx a collection of often unrelated segments - horribly criss crossing each other.
I once tried writing an app to fix those sudden leaps, but in the end gave up.
The kml format may be a better format - on google earth you don’t see the problems.I have no idea if you can import kml into Qmapshack
Good Luck