Quote "Direct attachment of the sling swivel to the barrel band mount screw ideally would provide the most strength, but appears to cause difficulty with design to accommodate that."
Not necessarily, it could be the easiest attachment, if the
swivel is heal be a single screw. I have not tapped these nuts yet. if you find a swivel that uses a 1/4 inch or 10-32 screw in the center and is meant to be full tightness I can tap the nut with the appropriate thread.

Quote "If the swivel stud can be installed relatively close to the barrel band, wouldn't the rigidity obtained by the stock's attachment to the barrel band provide adequate strength to prevent stock fracture?" This could work as well.

What to do with the hole in the bottom of the stock? A pain 7/8 countersunk washer would not look right.  I like Dick's term escutcheon, so lets call it that instead of washer. If you like the color of the aluminum bonze in the photo, I could round the ends and drill the appropriate hole in the center to be a relative snug fit to keep it from wallow then letting your swivel get loose. I have a small pile of these aluminum bronze ends from a production job we did 20 years ago. It does not seem to tarnish or discolor with age. How would you or a gunsmith make the inset in the stock for a escutcheon? I would do it on a milling machine, but it has been done other ways for centuries now.
The band took a set from forcing it on to the barrel I was able to pull the nut out of the band easily and have no doubt it will install as easily. It does have enough tension when installed that it will hold the nut fairly tight when lowered into the stock and be located so you can start the screw.

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