Honestly, I see the hips needing the most work - particularly the abductors and adductors. Reed did mention that you should move your stance out a bit and I still see this being beneficial to strengthen your hips. But I understand that it's causing you pain so you can probably work around this by doing Bulgarian split squats.
As your adductors/abductors get stronger, keep focusing on opening up your hips while still keeping everything tight. You may be able to open up your stance a tiny bit. Not something you have to try yet. It'll be worth a try after a few months of consistent Bulgarian split squat work. It may not even be necessary to open up the stance width much if you can open up the hips a bit more with your current stance.
For now, don't change anything. Just add the Bulgarian split squat work for the next few months and then see where you're at.