I’ve modified themes/hugo-lithium-theme/archetypes/default.md to include the setup2 chunk. Thus that chunk gets automatically added into a new blog post created with the addin. This goes into all new posts, so will need to be deleted in md files. I made a second archetype that was a copy of the original, but it doesn’t seem to be available from the addin menu.
Looking into this, it seems like it should be available; I’ve posted a question on stackexchange.