I have cut the tapers in all four mast staves. Now to cut the rabbets in the two side pieces.
The manual suggests for each rabbet making two cuts with a table saw. My side pieces have a noticeable bow in the last several feet, so I worried about being able to keep a long, thin, narrow piece of board straight and flat through the saw for two cuts that have to match up.
I have these great angle iron benches to which I could clamp the sides flat and then use a hand router to make the cuts. This felt like an option that would give me more control and a cleaner cut. Another advantage would be that this is something I could do by myself at my leisure, whereas I would want another set of hands for the table saw. The downside to using my router is that I don’t have a single bit that would make the cut. For the bits I have, it would take 2 different bits, 2 passes each. So 4 passes for each rabbet, with all the adjustment and such that’s involved each time I change bit, depth, guide rig, etc.
In the end, a friend suggested I use his dado stack with my table saw. I had not used one of those before (nor really knew what it was) but it seemed like the best option. I would need a helper, but it would mean a single pass for each rabbet and only one tool setup.
To ensure I’ll never use a dado stack again, I spent 45 minutes building a rig to which I can mount sacrificial fences. I had some nice straight pieces of MDF laying around that were already cut to the size I needed. So I cut and screwed that stuff together to make a box that fits snugly around my saw fence. To that box I screwed a strip of board that will be my sacrificial fence. When that board gets torn up I can simply unscrew it from the box and attach another. Here’s a picture…
There are much simpler ways to mount a sacrificial fence. But I happened to run into a professional cabinet maker and this is how he said he did it. Plus I didn’t have the right clamps to do it the easy way.
You’ll notice in the picture above that I do not have a proper throat plate for the width of the dado stack. The stupid thing is that I actually had one on order, but I came upon a block of time I could get this done and also have someone to help. So I ran the sides without a throat plate.
I used a proper pushblock and was terribly cautious but it still probably wasn’t the safest thing to do. However, the real problem was the cut quality. At the tapered ends where the width of the board is narrower than the blade opening, I wound up with some sloppy cuts. They really aren’t that bad and definitely just aesthetic. Nobody will notice at the top of the mast.
Ultimately, for anyone wondering, I would go with the dado blades if you have them. But definitely use a proper throat plate.
Cleanup and Dry Fit
In all, I was very happy with the rabbet cuts. But they needed a little cleanup. So I clamped the two sides to the aft face and went down each rabbet with a block plane.
One side cleaned 
Both rabbets cleaned
Below is a flyby of the dry fit. Note the messy mast top. Other than that, pretty good I think.
Next is the glueup. But if you notice from one of the pictures above, there is a sight bow in the top of the mast. I’ll need to clamp the mast such that it will cure straight.