Most of my modelling is in 4mm, this will be no exception. The plank will probably be only 6"-7" wide and a couple of feet long. If I can manage it, it will also be incorporated into a cameo-style layout, at some point.
So there will be a quay wall, but no water, and the buildings will be an inch or so deep.
One item I'd like to include is a 'working' sack hoist.
Meanwhile, I've been looking at potentially suitable bits of 5mm ply and 2x1 in the wood pile.