Implement a human readable protocol, then use standardized streaming compression on the wire to get your message size down. Something LZ family because there are tools everywhere that speak them. And consider turning off transport encoding for local development.

Being able to scan data saves so much time on triage. And using zgrep and friends on production data is almost as easy. You will spend tons of effort trying to make something 10% more efficient than zlib or for certain zstd, and the cost is externalized onto your team.