Hi! You can ride the routes from either direction. But I should note the southern explorer is for a bikepacking set up with a bike you can carry in places. If you have a heavy bike set up the routes you selected are unwise to ride.

I do not have a particular recommendation when it comes to the direction. Look at the altitude gain and decide what is best for you. For example, the Wilderness route has less climbing if you start in Trondheim. The prevailing winds in Norway come from the southeast, so more chance of tailwinds starting in Stavanger for the southern explorer. But I really don’t think it matters that much.