Latest conversations here and next to the code repository have led to many improvements in the code base which respect the rationales above, and caused a new release v0.9.0.
https://github.com/boringproxy/boringproxy/releases/tag/v0.9.0
It was also influenced by thoughts in https://dev.indiebits.io/t/rereading-documentation-client-arguments-largely-redundant/39/4