Well, I've done 4 coats now and I'm leaving it at that. bear in mind that I originally approached this with the mindset that I was going to hand brush some grey primer on this panel so it wouldn't stand out too much.
Pics are of the paint after wet rubbing the 3rd coat with 800 grit. Notice I didn't take back all the orange peel- I was worried I'd start to find the old paint. Since I had pretty much made up my mind I was stopping at four coats, it was a compromise I was willing to make. Next pic, 4th coat. Always hard to see in a picture, but the orange peel is about the same as you see on some new cars nowadays, and less than some back yard jobs i've seen. this is more than acceptable to me. note the effect is much closer to the classic sprayed orange peel than to rollered wall paint orange peel. The fuel filler well was painted with a trim brush.
What I'm a little annoyed about, but will learn to live with, is that I didn't 'melt' one section into another as smoothly as I thought. This is what the third pic is showing. It wouldn't be a concern at all if I was definitely going to cut and polish the paint. But in general I like the look of it as it is, so that line (there are two actually) may be annoying. Or maybe, it will become less noticeable over time. Enamel takes a long time to really harden, and I bet in doing so, it becomes just that much thinner...
All in all I'm very happy with how it's turning out. I won't be putting the panel on until later in the month, even though I'm now itching to do the whole car. On the 20th, I am taking The Master to a VW rally, as is

Will give my 'fender essay' one last huzzah before it comes off...