Like the look of that, but I'd put the chances of being able to travel by April 2021 without taking 6 weeks of holiday and spending most of it in Quarantine somewhere between Zero and None.
Can't see the route in Detail but the first loop sounds like I've ridden a fair whack of it, certainly most of from Hoek to Bergen-an-zee ish and part of the return may match what I did from Bergen to Delft.
I may have ridden some of the bit in Zeeland