I am a coach and "ex phys guy". And am a much better coach than I ever was an athlete. I have about 20-25 runners at any one time. Quite a diverse group: among them young guys able to run low 3.50s for 1500m and sub 8.25, for 3000m, one female 2.36 marathoner, a 2.27 vet and just recently a couple of guys looking to run sub-2.15 marathons next year. So it is a nice mix, and makes for interesting coaching.
To go into your questions on "purely aerobic periods", I once talked with one sub-2.28 female marathoner and she said than in the last six weeks before her PR she never ran faster than marathon pace.
We would never do vVO2max sessions in the build up to a marathon. Or maybe just a one-off for the athlete to have a bit of fun running fast.
You M-pace sessions look good, but 22 miles? Are you looking to break the WR? I used to see Gelindo Bordin doing these runs in lower-key marathons where he would stop at 20 miles (after being quiet in the second pack of runners, never competing) and get in a car. But longer than that? My wife, the 2.36 runner, does up to half marathon at this pace, but we have never found a need for her to go longer. Although we do make sure when she finishes that she is fresh enough to go further.
About "running Nats", what distance is this? Are you an important counter in the team? Can you not just run it off distance training (with some sessions of 5 x 2000m or 3 x 3000m repeats at 10k pace)? Those will make you strong. If you want, stick in something like 2 x (8 x 400m) at 3k pace with 100m jog recovery in 30-40 secs and 800m jog between sets. These will sharpen you up pretty fast and can be good fun.
About "destroying enzymes", your body adapts to the particular stress placed upon it. Give it miles and you become an aerobic animal, give it lots of anaerobic work and it will adapt to become better able to provide energy anaerobically. But just adding a couple of weeks of sharpening on top of good aerobic work will not do this, and between Nats in Dec and Motorola in Feb you can get back into some solid marathon-pace training.
I live well south of Rome, but am on the same time zone. My wife is from here and I have lived here for 20 years.