I've seen Nathans stocked in Europe: there is a kind with a fabric handle round a normal plastic waterbottle and you just shove you hand through the opening. It stays on your palm with a friction fit.That way I would more precisely call it "handheld fingerfree". Also I think I have seen the brand Rucanor that has a bottle shaped more like a doughnut so there is no need for the fabric but OTOH (no pun intended) there is no give in the hole like with fabric.
I would cut down to say around 40 km per week, e.g.: 5 miles slow, 4 miles tempo, 5 miles slow and 12 miles LSD. That's about 5/8ths of your peak and lets you ramp up again starting some way into the previous programme you used. It's a benefit for the long-term good of the family that you remain fit and I think less than 4 hrs per week is modest in relation to other habits.
I walked it last year in 17 km to 36 km chunks. Main bags transported by a baggage company. I have the tracks on Garmin Connect linked below - you could download them to a watch.(They might include some diversions to B&Bs)
There was a lot of rain in 2012 and I remember of lot of muddy sections and also scrambling under hawthorns where we insisted on keeping to the dyke, which often forms a boundary between fields. I used alternating pairs of Salomon trail shoes. My one luxury would have been an electric boot drier. I agree about the Tintern section, but we got through OK but it made the longest day into 36 km with a bit of going wrong.
I remember thinking I wouldn't want to run it, but I think differently now with a better base and having run the Jurassic coast. Our stops (with a few comments in the linked tracks) were:
Can't see the connection why you think minimalist shoes are the answer to dodgy knees - care to explain? In the meantime, I'd try to keep an eye on the two separate variables stack height (amount of cushioning) and heel to toe drop. If you want to stick to a "bit" minimalist then there are a few shoes with 4 to 6 mm drop with have everything from very little to a lot of cushioning. Going straight to zero drop is likely to give you a different type of injury unless you take a long time for the transition.