Manfred, you are right. This was really a pitty! It is impossible to shoot at golden hours in the trekking, as the park has strict rules about the time in which trekkers can walk the trails. They "close" at 17:00h and are controlled by the park rangers. Since golden hours are about 5:00am and 21:00 (due to the latitude), and considering the interesting points are in the middle of your daily walks, you are forced to shoot most of the places during the day, with not ideal light conditions (as you mentioned).
Cheers,