Could Japan fight only to force a negotiated peace?

Was Japan's best hope to hurt the Allies badly enough to force negotiations rather than expect an outright victory?

Yes. Negotiated survival after inflicting heavy costs is Japan's best plausible outcome in the scenario.

A commenter distils the scenario into a limited Japanese war aim: survive Allied blows, cause enough pain to open negotiations, and avoid fading into strategic irrelevance. In this reading, that is the high command's best plausible outcome. Tactical success and attritional damage still do not create a credible path to final victory. The scenario also assumes that Japanese naval leaders understood the unfavourable material balance.