Hate to disagree with you but sadly in this case I do, and probably mostly due to climate differences. Your advice closely mirrors what they would tell you in Canada, as does your climate.
In the UK you can generally open up and give a remedial feed of fondant at any time in winter if they were left shortish at the outset, and on mild days any time in poly hives they will take a little invert syrup down.
We did actually experiment with groups on the 'feed till they will not take any more' model, and others on the '14kg only' model. Thats 10 litres of invert syrup btw if you wonder about why such an arbitrary figure.
The lower feeding regime of the 14kg groups raised more late brood and were stronger in spring and had a considerably lower winter loss rate. the ones that were too heavy sometimes just got too small by spring crossover point (the time young bees hatching starts to exceed old bees dying). Now we never feed to the point of being stuffed full. Might seem counter intuitive to some, but its they way it pans out. Feeding till completely full is not what gives the best results, and not just for brood amount, as the bees like a significant area of open cells where they cluster very compactly, both on and in the cells. .
As for adding foundation. September in particular is a truly great month here for getting new combs drawn in the nest whilst doing the winter feeding. Not a drone cell on them. We get three to five new combs drawn in almost all our early home hives (up to 1st week Oct in wood, third week in poly) It will all be down to the maritime climate. Yet they do even more radical things in Denmark and Norway, where they can put them into winter on all new wax and feed to get it drawn.
ps....it is very unusual, if we have fed the 14Kg, for the bees to need anything more feed wise before the spring feed window.