You will find that the track/road is surrounded with catch fencing. However, at every location that has a good view, they have very thoughtfully provided cut outs in the fence for photographers. the cut outs are not very tall, probably only 200mm but are quite long in most places, at least a metre. As you will only be panning horizontally, they work out fine.
One of the more iconic areas to photograph is from the bridge in Adenau. You can walk up steps at that point which lead you up to the path around the track and several corners are easily reachable from that location.
Have fun, its a great place to be.