I forgot to mention that when I made the Couronne this weekend I found myself without a poolish, something I rarely forget to do.
I decided to start one at 8 AM. I used 1 cup whole wheat flour, 1 cup water, and 1/2 teaspoon instant yeast, which is a bit more yeast than I'd do in an overnight pre-ferment. I then placed the covered bowl in the just-run dishwasher which, being warm, moist, and clean, is about as close to a professional proofbox as one can find in one's household.
I left the pre-ferment in the dishwasher for 4 hours or so, then I used it as the base for my final dough, which had a tablespoon of salt, 3 more cups of bread flour, another teaspoon or two of instant yeast, and a cup or so more water. I totally winged it, adding more flour and water until it felt right. The dough was quite slack, but I didn't want to end up with a whole grain brick, so I decided to push my luck.
I gave it 3 folds a la the Hamelman method, then a final shape and rise. It was probably the tastiest wheat bread I've baked. I definitely will be trying the dishwasher method again.