Got serious and put my knoggin to pressing out the hub from the knuckle to get to the rear wheel bearings. As usual, once it's clear, it's easy.
Beacuse of the somewhwat curved shape of the knuckle, it wasn't terribly obviously how to place it on the plates. The base plates really aren't necessary, they just give more clearance. Using the plates that came with the press on their sides gives enough clearance. You have to futz a little to get the knuckle to be in a balanced position, but one it is the 20 ton press pops it out like nothing.