Several photos on Strava.
I started the long distance walk route around the national park on August 4 2019 at 7:10 am local time (GMT+2). The route has 5 entry gates, I started the run at the gate called 'Mechelse Heide'.
I did the route completely unsupported. I did not have any outside help nor I used a drop bag. As the forecast predicted almost 30°C and there are no natural water sources on the way, I carried 3,5l of water with me. The total weight of my backpack was 4,2kg (see picture for the other stuff I took).
I followed the route exactly as signposted (the route is signposted very well). As a validation I took a picture at each entry gate (the picture has the original timestamp and geolocation in the metadata) and a lot of picture in between.
I eventually finished at 16:12 (or 4:12 pm) local time. I had a total of 73,95km and 528m of elevation (according to Garmin data). The final (elapsed) time was 9h4min17sec.
The route is very beautiful and mostly flat. I estimate about 90% was on trails. Some of the trails mainly existed of sand, which made it hard to walk or run sometimes.
I liked the day out in this splendid area very much, would love to do it faster next time. The heat and heavy backpack made it hard at some points. Maybe I consider doing this in winter sometime.