I found it fascinating that while the pivotal character in Time Enough for Love, (1976) is male, Heinlein chose female professionals as some of the main protagonists when a male would have done as well. It seems that in most of his books a female is expected to be competent in something other than being female. Even in The Moon is a Harsh Mistress (1966)where a drastic imbalance in the ratio of women to men would seem to imply that the women would not choose productive activities, when men were eager to provide them with anything they might need, some of the women chose productive occupations.
It seems that if you are going to be a female protagonist in a Heinlein novel you had better be competent at something besides wife and mother, although you don't have to skip wife and mother in the process.
Stranger In a Strange Land (1961) seems to be a bit of an anomaly in this regard. Jill is proactive early but this seems to be a plot issue rather than a role model issue. She is fairly conventional in role in the rest of the book as Mary Magdalene to the preacher/entertainer phase in Mike's Career. The other female characters are also quite conventional although quite capable. I suspect Heinlein felt he was being offensive enough in his main theme without tacking on any feminism issues.