How would I go about setting up private tunnels (like playit) for Fabric servers?

I think the simplest solution would be Playit, but I assume by the title, you're looking for a playit alternative?

I just don't think playit works on Fabric, I've found some outdated "unofficial" mods, which I wouldn't trust anyways, but they're out of date

From what I know, you don't need the plugin. You can install it on linux. https://playit.gg/download/linux

So... you can't install the software?

playit has a standalone software version ^^

I was worried about doing that because I have multiple servers running on the same machine.

I’m sure it’s possible though. Maybe I run containerized versions of playit for each docker server?

I’m not sure, regardless I solved the problem I wanted to use playit to solve anyways.