I've done a few days of testing now on the bench, checking the ohm values at various points to make sure it did the right thing.  It totally does.  It 100% works.

Got a new MeanWell driver last night (the old one I was using was unsuitable for this, because at 100% it would have over-driven the LED's and at lower power ratings I would lose alot of precision in the steps between 0 and 100 %), wired it in, and this morning at 3am, looked, and I have beautiful moonlight at the perfect setting for today.

Woot!