Believe me or not, I firmly think that he will attack Hillary by saying she’s anti-woman. Follow me here - in addition to trying to reform the establishment behind him and reframing himself as a pragmatic business man, an outsider in the starkest of contrast with the insider Hillary. Furthermore, he could, in so many words, characterize Hillary as woman who not only lets her husband have affairs but works to silence the women as well.
Take that, putting American lives at risk with the email servers, voting for Iraq, voting for a border wall between us and Mexico, being a (IMO) ineffective SoS, being beholden to bankers, being establishment, and so much more, then you have a pretty well-thought-out attack on HRC.