Just replace your Sunday run with the HM at HM race pace. No need to make any other changes.
You wont do your best HM performance due to the high mileage week - buts that's kinda the payoff of doing hanson. Dropping your Sunday from 8 to 3 wont make a huge difference IMO as you will still have lots of other miles in heavy legs. If you are gonna drop it then drop it entirely.
Of course Tim Noakes for many years used to believe the exact opposite of what he is now promoting in terms of diet. Interesting to read the advice in the first 3/4 editions of his book compared to what he is advising now. Clearly shows for me that things aren't entirely clear cut.