Before planking the main deck, I needed to install the lower bulkhead separating the main deck from the quarterdeck and the captain and officers' cabins. Near as I can tell, it goes atop the officers' deck planking, so that's where I installed it:

I believe the aft portion of my main deck may be a bit lower than it should be, as the slots in this partition and the slots in the aftmost deck beam do not line up vertically:

That may also/instead mean my aft deck installed is too high, but to maintain the correct partition height in that area, I'm leaving it alone. I don't think the resulting quarterdeck will be too high, so I don't see any measure problems at this point (probably due to my lack of insight, rather than no problems actually existing).
The port waterway goes on first. I had to reshape the outer plank (waterway) a bit to fit the bow, probably due to my less-than-perfect shaping there.

When doing this, I actually forgot about it being a waterway, and just looked at it as another plank. My intention had been to raise it up a bit with shims, to simulate a thicker waterway with a slope to the deck. I didn't remember this until several planks were installed, so too late. I may try to do something about it later.
If you're wondering about the heavy paper taped in place, I've already dropped a couple small pieces down into the hold, and was lucky enough to get them back out. I'm trying to prevent that in the future; I don't think the model will take well to being shaken upside down!
Here I'm gluing the second plank in place:

Up to a point, I could use clamps to keep the planking tight, with weights to hold them down.

When the clamps quit working (I broke one of the black needle-nose ones), I just used weights and sometimes pieces of scrap to help hold them:

I fit the last plank that contacted the mortar surrounds to them, and glued the surrounds as well as the plank in place.
Making sure the mortar housings and surrounding planking are glued in place true and level. And secure:
This was the last full-length plank. After this, planks will be in pieces for each section between mortars and hatches and such:
Where I am at this point:

I've already located the main pumps and have a plank partially cut for it. From now on, I have to start thinking about all the required openings for pumps, hatches, etc. Looks like the Bowsprit Step must be positioned and glued to the main beams, with planking surrounding it, which I have to watch out for. I thought the step on it might go atop the planking, but looks like it doesn't. That's my interpretation, anyhow. The instructions show full planking everything, and cutting all openings later.
I didn't end up reducing the planking width as suggested on the plans to speak of, just enough to go aside the windlass mount, so am a bit surprised that the overall planking half doesn't quite make it to the centerline. No problem, though, as I won't be planking much of the starboard side of the deck.
Sounds like a good place to stop for the night; too much thinking and planning involved at this point. Good night, and thanks for watching!