Advice needed regarding clinical sup position

I have been an ER nurse for almost 3 yrs with 4 months off for maternity leave. Also, I have been a charge nurse for a year. I work in a small hospital where we are always hurting for staff. I currently and always have worked nights. It is taking a toll on me not spending the evenings with my family. I have my BSN as well which not many people have at my hospital, including the director. My hospital mgmt is such that there is the director and 2 clinical supervisors. There is an opening for a clinical supervisor job. I have talked to my director and told her this is what I have always wanted to do and that I think I would learn fast and do a good job. Also, the outgoing clinical supervisor who is the director's best friend, also recommended me for the job. Of course there is a huge interview process with the director and the other clinical sup as well as a panel interview with other clinical supervisors.
My concern is that the director has stated to other staff members that she doesn't think I would be happy in that position. Also, she is concerned because we are always extremely short on night shift and especially for charge nurses. One is going on maternity leave and both myself and the other are applying for the job!
I am upset because I feel that even if I do awesome in the interview process, I will not be hired. Staff have "talked me up" to my director as a wonderful resource, etc and I don't think she wants me to leave the noc shift as charge.
So even though I am furious that these concerns are coming into the decision making process, that I feel are irrelevant, I want to do well on the interview.
Any advice? What should I practice on? What should I focus on? I have been told to talk about utilizing the experience of other clinical supervisors to learn the position and also to focus on networking with departments in the hospital. And throughput was up there as well??? Any other suggestions???
Thanks for reading my long post!