I carefully looked at YOUR spreadsheet, and I think it is pretty accurate, especially the anticipated average speeds.
I think of two categories of very small voyagers:
The smallest, I call "micros". They have a Length, Beam, and draft sum of 20 ft or less. And they displace one metric ton or less. An around-in-ten boat would fit this class. Gerry Spies'
Yankee Girl fits this bill (10 ft + 5 ft + 2ft, IIRC.) Although such a small vessel may be seen as a stunt boat, I believe it can be made to work as a real ocean crossing sailboat.
The next size up would be what I call a "mini". It would have a Length, Beam, Draft sum of more than 20 ft, up to 30 ft, and a displacement of more than 1.0 metric ton, up to maybe 2.0 metric tons.
Most of Sven's creations, including his present one, fit this second category. A whole lot of other boats, including one which sailed around the world, do too.
By "draft" I mean fully extended draft.
By "displacement" I mean the fully loaded boat.
I have seen that speed is often mentioned as a primary safety concern. I agree to some extent. But I think it can be somewhat over rated.
Suppose you had a choice between two vessels. One was say 50% faster than the other. Now, let's suppose that the slower one is all but guaranteed to recover from a 180 degree capsize, but the faster one isn't.
Which vessel would you choose to make an ocean passage in?