Ted Molczan has provided a table of expected magnitudes for the spacecraft (Orion) and the SLS upper stage and spacecraft adaptor (the Interim Cryogenic Propulsion Stage) on seesat:
They indicate that Orion will be 13th mag on the night of launch fading to 17th mag at lunar distances with the ICPS around 1 mag fainter.
The ICPS will be deflected from the spacecraft trajectory by a disposal burn shortly after trans-lunar injection (TLI). This will target a lunar flyby which will put the stage into a heliocentric orbit. The stage will probably do a propellant dump shortly after the disposal burn as part of its passivation procedure. Sadly we are not going to see that from here but it could be an interesting sight for people in the right place. Have a look at Chris Taylor’s description of the equivalent from the Apollo 8 S-IV-B upper stage:
JPL Horizons has an ephemeris for Orion but not the ICPS. It is likely that an ICPS ephemeris will appear here:
Good hunting. Please post any images you get on this website.