The only problem is... people might ignore posts they can't see, if they have no CR with the character/pre-existent interest.

One idea might be: put the whole body of the post on the comm, disable comments, and have a link to the mirrored post on your journal that people can follow to reply.

It's also not aesthetic, but at least, I think, it might make it easier for people to become interested in those posts, versus potentially scrolling by.