Please note that I'm asking about a thread on this meta (Forum tone, reasonableness, and the possibility of a curated stack), not for general use within ELU. I will be needing more than 600 characters for sure. Do I answer my own question and put it there?
You don't respond, especially if the response is that long. Stack Exchange is not a discussion forum.
More in the way of discussion is inherent in Meta, but a post which is longer than 600 characters should really be crafted into its own entity. A response that long to an answer implies a contrary view; a response that long to a question implies it's really an answer.
Answer your own question with the answer you think it should have, and let the community vote on the alternatives thus presented.