Technically, there IS a cameo of an actress playing Mara -- supposedly sent to Jabba's to stop whatever plan Luke and his friends had in mind. The proposed scene was of her posing as one of Jabba's dancers, but she was left behind instead of joining the party on Jabba's sail barge.
As such, the short scene of her was cut from the final print of the film. But to clarify, Mara was pretty much depicted as she appears in the novels: human, fair skinned and a redhead.
-- Stephen