As for the Centaur V thing, I'm clueless. If Arty 3 and 4 only need a "Block 0", (i.e., just an adapter of the proper height where the ICPS would go), then Arty 5 (presumably a Blue Origin mission) ...
So, for my book to be adapted into a Summer Movie, I need both SpaceX and Blue to test takeoff from the Moon as requested by NASA for their demo, but show off with a second soft landing, in close ...