So as a practical matter, assuming you are able to figure out the
misleading nature of the clearance, what would you do?

This is a difficult question when the ATC guy doesn't understand the
approach. Like the case I mentioned at my own airport, ATC vectored
us at 2,500, but expected us to descend to 2,000 once on the
localizer, even though the chart didn't permit the descent.

My requests for "lower" were met with a bit of disdain when the
controller told me to fly the approach chart, which he *thought* said
2,000.

Some of your suggested dialog makes me a little uncomfortable, because
it seems to lend itself to some miscommunication between ATC and the
pilot about who is providing terrain clearance. (This was the essence
of the TWA514 accident.)

I suppose the easiest answer is to ask ATC to inform you when you're
within 10 nm of the NDB.