Well, I added that other layer of the persimmon knit, and wore it to work one day. I did not like myself in it. I was pleased that it came out well - it's interesting to try to copy something from scratch, but it didn't look well on. Surely it could be fixed in some way, but how? I left it hanging in my closet.
Then we had a mild spell last week and I was panicked that there weren't enough in-between-the-weather-extremes pieces in my wardrobe. I saw it hanging there and put it on. Immediately I could see that it was too long, so I cut off two inches (these knit styles are great - no hemming necessary) which gave the whole a better balance. I also modified the "points" at the sides, which seemed a little too extreme.
Now I have a new dress that looks good, is very comfortable, and I like it. And rather more "sedate" than the original. What took me so long?