I'd probably just head out onto the pier at the Hoek. In fact, parking up as far as one can drive at the Hoek (there's some bar/restaurant where you can park), then wander down the 'causeway' towards the pier. It's a long walk, granted, and pretty arduous in the winter months, but you can get a decent vista looking into the Waterweg and out to sea, and of course over to Europoort.