It appears that there is no way to control the ordering of public/private entities in the docs.
I have a few important mixins and a lot of (private) helper functions. Whilst I would like the private functions to appear in the docs, they currently appear before all the mixins which are the lib's API and much more important. I was hoping that the access item in the .sassdocrc would control the order as well as the visibility, but the order of items seems not to effect the order of the entities in the docs.