No problem routing along the coast. We used this route on the way to Denmark and Rotterdam cleared us down to 500 foot to avoid holding for traffic from Valkenburg. We just routed a little way offshore so as not to cause any nuisance to the kit flyers and windsurfers.
Interestingly as soon as you get north of Den Hag(?), the minimum altitude is 1500 as all the islands are classified as nature reserves. Dutch Mil cover this airspace and a suitably relaxed about VFR traffic