I don't understand why somehow how you would think there will be any AOA derm positions to serve as your backup plan. Given the fact you only have Step 1 scores, you are likely a 2nd or 3rd year. Hate to tell you this, but I don't think AOA Derm Programs will be there for you.
As of April 9, there are only 8 pure DO Derm programs left (down from 30 a year ago). The rest are either closed or ascended to the higher plane of ACGME Accreditation. For your purpose, the Ex-DO Programs are no longer AOA and they are as out of reach to you as any other MD Programs. If you think the newly Initial Accredited ACGME Derm Programs will take you just because you are a DO and forgo the 250+ MD applicants, then you must be related to someone famous.
As for the last 8 DO Derm Programs, they have to get special permission from the AOA and AOCD just so they may recruit for the upcoming application cycle of starting date July 2019. Some of them may choose not to do that and just wait for next review committee meeting prior to any recruiting effort. Therefore effectively, this is the very last year for DO Programs to recruit with special permission. I foresee that you can only apply as an intern and not as a 4th year. Your high COMLEX score won't help you whatsoever because there will be no DO Derm Program for you to apply.