You're right, there are no full character replacement mods yet. There is one in progress for Kenzie Reeves on the Discord. But a new core character is a MASSIVE undertaking, each one involves hundreds of media files (including audio), and tons of code. I am curious who the first team will be to go through and finish one.
Aw thanks! When I release the playtest, it is usually first as an offline file, and then once the main bugs are resolved, I make the playtest available at a secret URL so supporters can play it online. I am hoping to get the playtest out tomorrow, but there is still so much to do...