So, my scale finally arrived, and I got a banneton for proofing as well. I've been experimenting a bit, and I think I finally got it. Since all the folks here were so helpful, I figured I could contribute by sharing my results. Would really love to hear your comments too! You can see the final product in the photo above.
In the morning, take starter from the fridge and feed it 1:1:1, i.e. equal amounts of starter, water, and flour. Cover and let it sit in a warm place for 6-8 hrs.
Levain (100% hydration) - 50g starter, 50g warm water, 50g KA WW four, mixed in the morning and put in warm place.
Water - 280g + 20g for salt = 300g total
Flour - 450g KA BF
Salt - 10g
Flour - 100%
Water - 71.5%
Salt - 1.9%
Mix everything (except salt and some water) until all flour is absorbed. Cover and let stand for 60 min, then add salt and remaining water, and mix for 3-4 min. I use stand mixer, but you can use anything you like.
Place the dough in a lightly oiled bowl, cover, let rest for 30 min. Take it out on a lightly-floured surface and stretch and fold from 4 sides, then put it back in the bowl. Repeat rest and stretch and fold 3 times (4 times total, cover during rest). BF for 2 hrs. On lightly-floured surface pre-shape, let rest 10-15 min, then final shape.
Flour the banneton, and the surface of the dough (lightly), place the dough into the banneton and cold proof overnight (10-12 hrs). Next morning, take the dough out of the fridge and let warm up on the counter for 1.5-2 hrs. Meanwhile, preheat oven to 500F, then drop the temp to 475F. I baked at first under a "dome". I have this old cast-aluminum pot, which I preheat in the oven and then invert and cover the dough with it to create hot and steamy environment, similar to a Dutch oven or Cloche. It looks like this:
I am baking right on a cookie sheet, lightly covered with corn meal to prevent dough sticking. Take the dough out of the banneton, dust off any excess flour (I found that I really don't like the taste of the roasted rice flour, which I use in my banneton :-) ), and score the bread. I scored at a shallow angle, trying to create an "ear". I think I succeeded.
Bake under the dome for 20 min at 475F, then drop temp to 460F and bake uncovered for 20 min more, rotating once in the middle. I waited for about 2 hrs before slicing the loaf, and I must admit that was torture! :-) The crumb looks fine, although I would prefer it a bit more airy. The taste was wonderful, and the crust was the crunchiest I ever achieved!
Hope this helps someone too!