Wait, I didn't have to go to Hunter's March? I thought there was nowhere else to go, however the sudden change in difficulty made me feel I must have missed an area.

Yup! I saw the big guy guarding the entrance and noped out of there, only recently went back - with hover, dash, wall climb etc, different moveset (no directional downslash).

I think I went through the narrow to the balloon place, then maybe back through the marrow or something up to Bellheart, deep docks etc.