I think you're right.
Body corporates can be expensive and not having one is foolish. Even with townhouses I anecdotally know someone whose efforts to remediate their leaky house took many more years/dollars than it should have because the overseas owner of the abutting house kept refusing permission for things to do with their shared wall and roof section.
I think the section/lot is too narrow for that though. Realistically the non-detached option is probably "townhouses" which are increasingly prevalent in Auckland.