If I return a token unit from Ripper's Bay to my hand, can I trigger Ripper Bay's effect?

Yes. The token counts as a unit for the trigger, so Ripper's Bay's ability fires.

The token moves to your hand (zone change happens first), which satisfies "When a unit here is returned to a player's hand." Only after that does the token cease to exist in the hand zone, which doesn't undo the trigger. You may pay [1] to channel 1 rune exhausted (FAQ #11023).