As I said, I am no longer involved with this TT, having split with the now-full-owner. (He bought my half of it.)
I was just trying to figure out the best way to do it myself if I buy a RV in the future.
The TT is a basic Gulfstream Amerilite. It never occurred to us that the WH would NOT drain through the low point drains. We had the faucets open while draining. It did drain slowly but the amount of water seemed to confirm that the WH did drain.
If it was not drained, it definitely would have frozen under the storage conditions.
I believe it's an Atwood WH, am not 100% sure.
So the moral of the story is, some WH might drain through the low points, but not all will. And the anode should be checked regardless. (I don't know if ExBF has done that or not, it's not really my concern any more.)