Q1) Yep, my wording was off – I also meant substitute AP flour for cornmeal, not add. I usually make flour changes in the 15-20% range so I can get a satisfyingly noticeable difference lol. So 75-100g substituted in a 500g flour dough. Go with whatever you feel comfortable with, of course.
Q2) The beauty of bread is that it can be made in massively different climates. And some of the excitement of sourdough is it’s inconsistency compared with commercial yeast (measureable number of microbes in a packet). Even when we nail down the same time and temp and grams of starter in a recipe, everyone’s starter will still be a little different.
Maybe aim for imitating the temp that you did in round one, since you’re familiar with it, and just change the amount of time. Or pick something that you suspect will work with your schedule for a typical day (cooler and longer?), but do it on a day you can check on things periodically, so you don’t end up with dough-soup. Then extrapolate from those results.
You’re welcome! I’m so glad I could help. I enjoy seeing these recipes come alive in other people’s kitchens. And I agree about the shaping – what a joy. I can’t wait to try it with an einkorn or rye.