I finally figured out the "why" as far as Xerxes barking. He's got a mild case of SA. He used to deal with this by chewing up my blankets (I have surgically precise incisions in two of them.) I began putting them away during the day: that's when the barking started.
So the solution thus far has been: Give him an appropriate blanket to destroy, sonic anti bark collar, and hide treats throughout the house before I leave every morning. Now when I come home in the afternoon, he's sleeping peacefully and I actually wake him up. No more complaints about the barking, and as soon as we get back from the morning walks he's off to search for treats.