Patching the “Mod era” in between the 20th and 21st century timeline would do the trick: have the Crisis depower her (except for her unaging) and have Steve disappear (in the Mod era, he died but was later restored to life), and have her do the “Mod era” stuff until Superman debuts and a means to restore her powers becomes available: maybe the new Heroic Age gives her a way to do an Orpheus-style raid into the underworld where she finds Steve's spirit and brings him back, restoring him to life and in the process regaining her full powers.
Frankly, I find the detractors of putting her Golden Age history back in to be overly pessimistic, always talking about what can't be done instead of looking at ways that it might actually be doable, or assuming that the only options are the dumbest ones.