ILR in Japanese passport instead of TR rights

[LaxUSIN]

Hello. I'm a Dutch & Japanese dual citizen exercising TR rights in the UK using my Dutch passport for the last 1.5 years. My dad is a British-Dutch dual citizen (British citizenship acquired after my birth so I'm not).

I'm required to renounce one of the nationalities before I'm 22 (I'm soon to be 17). If I decided to keep my Japanese passport, would it be reasonable to avoid all the post-Brexit temporary residencies and settling, instead use my Japanese passport to settle in the UK using the fact that my father is a citizen (SET-F)? It would cost my dad a bit more and the rules are a bit unclear on the 2nd parent - my mother is a Japanese citizen living in Japan and I live with my dad so I think this satisfies the sole responsibility requirement?

I would appreciate any input.