I tried posting this on Kemono's chan board, but they block Tor apparently, so I'm screaming into the void here. If anyone knows an email list or something, I'd love to know.
I've been thinking about how you could get around the Fanbox/Subscribestar/etc. restrictions, and I think the only real way would be to use a browser plugin that literally acts as a simple proxy. You could make it robust to MITM attacks (people uploading garbage) by sending your tokens over to Kemono and then have Kemono make the (encrypted) network requests via your computer as a proxy. Unfortunately this would mean that importing would more than likely be slower because it would depend on the speed of the leaker's internet. But the upside is it could (with standard precautions) be practically undetectable and wouldn't suffer from the trolling problems that come with manual uploads. The huge plus side is that it would probably make scraping slightly more accessible because people wouldn't have to fiddle with the inspector.