I think that one's figured out. At least there's a method to choose inside profiles, even if the old way no longer appears to work the way it used to.
However, the same process I originally described for how inside geometry could be chosen for Convert Entities also worked for Offset Entities.
Now, there appears to be no process whatsoever - aside from individually picking each entity - for choosing inside loops in Offset. I get both the outer perimeter of the parent (sketch plane) surface, as well as my offset.