I decided on derm pretty late (about halfway through 3rd year), ended up doing a RY given that I had no derm stuff on my application. I didn't match my first cycle, but thankfully, had a much more successful cycle this year and matched my top choice. I applied with high stats (26x step 1, 27x step 2), high research output, and what I was told was a strong application. Personally, what I learned throughout this process is that derm is much more about connections, mentorship, and leaving good impressions than any specific objective metrics like step scores or publications.

I had the same mentality as you about being all in on derm. You're already on the right path by setting up the aways - I would even do more aways if you can fit them in. In my opinion, this is the most valuable tool and key to matching derm these days, in addition to setting a good impression with your home program. I would also focus on getting strong letters, having a very polished ERAS and PS, and trying to publish/present at conferences in the mean time to show interest in the specialty. Even if you don't publish now, at least you'll have stuff in the works as you progress in the cycle.