Disclaimer: I packed about halfway.
These long nights through deserted country mean carrying lots of water and food, and not seeing a light for a while is disconcerting. The traffic free experience is wonderful, but if you were alone and Something Happened it'd be a good while before a vehicle came along.
Two of us had a Formule Un hotel for the first night, which made the second day less traumatic but most rode from 2pm on Thursday to almost 600k, then faced a day of 300k with 7,000 metres of ascent. There's no easy 1,000k, obvs, and that flat bit along the coast for the first afternoon is more than compensated for by the hills. Belgium is not a flat country, y'know.
Great route, well organised, deffo recommended. ☝