Just for the record, in case anyone wants to repeat these routes.
Dunkirk ferry to the Ibis hotel in Dunkirk via the quiet residential streets, avoiding the dual carriageways. Be aware there are two bridges to cross, these went up and down a lot, but might be left up (ie closed to traffic but open to boats) if you're riding in the middle of the night or very early morning:
View: https://ridewithgps.com/trips/16744826
Ibis hotel in Dunkirk to Ostend via Veurne (a pretty town square) for coffee:
View: https://ridewithgps.com/trips/16744827
Ostend-Gent - we stopped at the strange bicycle museum outside Gent - recommended
http://www.oudesmisse.be/
View: https://ridewithgps.com/trips/16744830
Gent-Leuven-Maastricht (note this is two days joined together) - you could cut a few corners on these days, particularly the first but we wanted to visit a specific town.
View: https://ridewithgps.com/trips/16744832
Maastricht-Eindhoven-Breda-The Hook - note at Willemstad we took the ferry which was far better than the huge bridge. Might not run out of season, best to check.
View: https://ridewithgps.com/trips/16744835
It was a good trip. If in future years someone copies them after doing a search, I hope you enjoy the trip as much as we did.