OK, a couple of new data points, neither particularly encouraging. After I posted last night's post, a little voice inside my head questioned whether I had read the scale on my voltmeter correctly, and sure enough, I was off by 10X - with fuse 27 removed, I'm getting a 400 mA draw (0.4V dropped across the 1 ohm resistor), not 40 mA, which would be 0.04V. So, while pulling fuse 27 does give a 10X reduction in draw from the 4+ amps I get with the fuse in, it's still nowhere near the normal baseline level of 30-40 mA or so.

Second, I removed the connector to the windshield washer pump after putting fuse 27 back, and the current draw is back up to over 4 amps, so that's another (inexpensive) thing to scratch off the list.

I have to confess to not understanding very well what's to be expected as far as current draw when the car is in its various modes. Doing the testing the way that I am, with the negative battery cable disconnected now for nearly a week, and measuring the voltage drop across a 1 ohm resistor placed in series between the negative battery terminal and its cable, what should I expect the current draw to be? What does it actually take to put the car totally "to sleep"? I would think that having the battery cable disconnected for nearly a week should do the trick, but as I said, this is an area I'm not very knowledgeable. Thanks in advance the the continued advice.

__________________
2003 X5 4.4i
1992 Porsche 968
2007 328i
2014 Subaru Forester XT