First off and as mentioned above, I’m of the opinion that this admissions cycle is a really good time to apply to Duke ED especially as an URM female in engineering. Last year, there were 500 less ED applicants from the previous year and I think that trend will continue this year as many applicants were not able to visit Duke this year due to CV-19 and will be reluctant to engage in a binding commitment having never visited the college.
With that said, I think your course rigor and grades are pretty good. I agree with you that taking the SATII Math and scoring high would be helpful as an engineering applicant. Note that 28% of the test takers score a “perfect” 800 so you want to prep sufficiently and get a high score. Duke going test optional is going to help give you a chance this fall but I would not rely on it too heavily as there will be lots of high stat applicants that will have great scores achieved before the pandemic hit in March.
I would really get to know your teachers who are going to write their letters of recommendation and give them a “cheat sheet” of your ECs, passions, and commitment to your education and career.
Your essays will also be very important, and should really tell the story of how you will make Duke a better place by having you on their campus. I would really research Duke’s club “Society of Women Engineers (SWE)” and showcase your leadership and how you will thrive in this environment at Duke.
Will you be in the top 5 or 10% of your class? Do they rank? Being a high achiever at a “below average” high school might just work in your favor.
Financial “fit” is #1 so make sure you run the NPC before commiting ED!
My last point is that you want to “package” yourself in a nice, neat bow tying everything together so that the adcoms will fight for you in front of the admissions committee.
Good luck to you and let us know how it goes…