VERY nice job FoxbaT. A lot of work but an excellent result.
Even if a bit oversized, once the deck is stained I think they will appear just the right size.
However, I think you should add a few more.
If you take a look at the photo that (Seewolf?) has on another thread (sorry, I don't remember which thread but within the last week, there was a photo with an inflatable raft on the deck of a U-boat with a water deflector at the front of the schnorkel slot), you can see that the planks have a few more attachement points.
You will find a fastener at the end of each of every plank where it ends at the edge of a hatch or where the bollards are set into the deck.
Take a look at your last photo, where the deck ends on either side of the stern running light fixture. There should be 4 more screw/plugs, 2 at each end of the running light. There should also be 8 at the hatch, 4 at each end of the hatch. 6 at the next, wider hatch (all at one end as there is another hatch right in front of it) and 4 at each bollard (2 each end).
Makes sense?